Airbag Deployment Control Based on Contact with Occupant

ABSTRACT

Method for controlling outflow of gas from an airbag includes deploying the airbag toward an occupant prior to or during an accident involving the vehicle, detecting contact between the airbag and the occupant by means of a sensor, and controlling outflow of gas from the airbag based on the detected contact. Contact between the airbag and the occupant may be detected by analyzing deceleration of the airbag, e.g., via an accelerometer arranged on a surface of the airbag, a pressure sensor arranged to sense the pressure in the airbag which is correlatable to the deceleration of the airbag and tension sensors arranged on tethers between opposed inner surfaces of the airbag. Outflow of fluid from the airbag may be controlled by arranging an exit control valve or vent in, on or in connection with the airbag and which is adjustable to provide variable outflows of gas from the airbag.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is:

1. a continuation-in-part (CIP) of U.S. patent application Ser. No.10/733,957 filed Dec. 11, 2003 which is:

-   -   A. a CIP of U.S. patent application Ser. No. 09/849,559 filed        May 4, 2001, now U.S. Pat. No. 6,689,962, which is a CIP of U.S.        patent application Ser. No. 09/193,209 filed Nov. 17, 1998, now        U.S. Pat. No. 6,242,701, which is a CIP of U.S. patent        application Ser. No. 09/128,490 filed Aug. 4, 1998, now U.S.        Pat. No. 6,078,854, which is:        -   1) a CIP of U.S. patent application Ser. No. 08/474,783            filed Jun. 7, 1995, now U.S. Pat. No. 5,822,707; and        -   2) a CIP of U.S. patent application Ser. No. 08/970,822            filed Nov. 14, 1997, now U.S. Pat. No. 6,081,757;    -   B. a CIP of U.S. patent application Ser. No. 10/061,016 filed        Jan. 30, 2002, now U.S. Pat. No. 6,833,516, which is a CIP of        U.S. patent application Ser. No. 09/901,879 filed Jul. 9, 2001,        now U.S. Pat. No. 6,555,766, which is a continuation of U.S.        patent application Ser. No. 09/849,559 filed May 4, 2001, now        U.S. Pat. No. 6,689,962; and    -   C. a CIP of U.S. patent application Ser. No. 10/227,781 filed        Aug. 26, 2002 which is:        -   1) a CIP of U.S. patent application Ser. No. 10/061,016            filed Jan. 30, 2002, now U.S. Pat. No. 6,833,516; and        -   2) a CIP of U.S. patent application Ser. No. 09/500,346            filed Feb. 8, 2000, now U.S. Pat. No. 6,442,504, which is a            CIP of U.S. patent application Ser. No. 09/128,490 filed            Aug. 4, 1998, now U.S. Pat. No. 6,078,854;

2. a CIP of U.S. patent application Ser. No. 10/931,288 filed Aug. 31,2004, which is a CIP of U.S. patent application Ser. No. 10/303,364filed Nov. 25, 2002, now U.S. Pat. No. 6,784,379, which is a CIP of U.S.patent application Ser. No. 10/174,803 filed Jun. 19, 2002, now U.S.Pat. No. 6,958,451, which is:

-   -   A. a CIP of U.S. patent application Ser. No. 09/500,346 filed        Feb. 8, 2000, now U.S. Pat. No. 6,442,504;    -   B. a CIP of U.S. patent application Ser. No. 09/849,558 filed        May 4, 2001, now U.S. Pat. No. 6,653,577, which is a CIP of U.S.        patent application Ser. No. 09/193,209 filed Nov. 17, 1998, now        U.S. Pat. No. 6,242,701;    -   C. a CIP of U.S. patent application Ser. No. 09/849,559 filed        May 4, 2001, now U.S. Pat. No. 6,689,962; and    -   D. a CIP of U.S. patent application Ser. No. 09/901,879 filed        Jul. 9, 2001, now U.S. Pat. No. 6,555,766;

3. a CIP of U.S. patent application Ser. No. 10/940,881 filed Sep. 13,2004 which is:

-   -   A. a CIP of U.S. patent application Ser. No. 10/061,016 filed        Jan. 30, 2002, now U.S. Pat. No. 6,833,516;    -   B. a CIP of U.S. patent application Ser. No. 10/174,803 filed        Jun. 19, 2002, now U.S. Pat. No. 6,958,451; and    -   C. a CIP of U.S. patent application Ser. No. 10/227,781 filed        Aug. 26, 2002, now U.S. Pat. No. 6,792,342;

4. a CIP of U.S. patent application Ser. No. 11/131,623 filed May 18,2005 which is a CIP of U.S. patent application Ser. No. 10/817,379 filedApr. 2, 2004.

5. a CIP of U.S. patent application Ser. No. 11/278,979 filed Apr. 7,2006;

6. a CIP of U.S. patent application Ser. No. 11/420,297 filed May 25,2006;

7. a CIP of U.S. patent application Ser. No. 11/423,521 filed Jun. 12,2006; and

8. a CIP of U.S. patent application Ser. No. 11/457,904 filed Jul. 17,2006.

All of the above-referenced applications are incorporated by referenceherein.

FIELD OF THE INVENTION

The present invention relates generally to methods and apparatus fordeploying a vehicular airbag and for controlling deployment of avehicular airbag and more specifically to methods and apparatus fortailoring deployment of a vehicular airbag to an occupant based in parton information obtained during the deployment.

BACKGROUND OF THE INVENTION

All of the patents, patent applications, technical papers and otherreferences mentioned below and in the parent applications mentionedabove are incorporated herein by reference in their entirety unlessstated otherwise.

Background information about the embodiments of the invention claimedherein is found in the '781 application, incorporated by referenceherein. Definitions of terms used in the instant application are alsoset forth in the '781 application, among others.

Preferred embodiments of the invention are described below and unlessspecifically noted, it is the applicant's intention that the words andphrases in the specification and claims be given the ordinary andaccustomed meaning to those of ordinary skill in the applicable art(s).If the applicant intends any other meaning, he will specifically statehe is applying a special meaning to a word or phrase.

Likewise, applicant's use of the word “function” here is not intended toindicate that the applicant seeks to invoke the special provisions of 35U.S.C. § 112, sixth paragraph, to define his invention. To the contrary,if applicant wishes to invoke the provisions of 35 U.S.C. §112, sixthparagraph, to define his invention, he will specifically set forth inthe claims the phrases “means for” or “step for” and a function, withoutalso reciting in that phrase any structure, material or act in supportof the function. Moreover, even if applicant invokes the provisions of35 U.S.C. § 112, sixth paragraph, to define his invention, it is theapplicant's intention that his inventions not be limited to the specificstructure, material or acts that are described in the preferredembodiments herein. Rather, if applicant claims his inventions byspecifically invoking the provisions of 35 U.S.C. § 112, sixthparagraph, it is nonetheless his intention to cover and include any andall structure, materials or acts that perform the claimed function,along with any and all known or later developed equivalent structures,materials or acts for performing the claimed function.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide new and improvedmethods and apparatus for deploying a vehicular airbag and forcontrolling deployment of a vehicular airbag.

It is another object of the present invention to provide new andimproved methods and apparatus for tailoring deployment of a vehicularairbag to an occupant based in part on information obtained during thedeployment, for example, based on information about contact between theairbag and the occupant.

In order to achieve at least one of these objects and others, a firstembodiment of a method for controlling outflow of fluid from a vehicularairbag in accordance with the invention includes deploying the airbagtoward an occupant prior to or during an accident involving the vehicle,detecting contact between the airbag and the occupant by means of asensor, and controlling outflow of fluid from the airbag based on thedetected contact by the sensor.

Outflow of fluid may be controlled to maintain acceleration of theoccupant's chest below a predetermined maximum value. The maximum valuemay be determined based on the forecast severity of the accident forwhich the airbag is deploying. In one embodiment, an average chestacceleration to cause the occupant to have the same acceleration as apassenger compartment of the vehicle in which the occupant is situatedis determined and outflow of fluid from the airbag is initiallycontrolled to provide the average chest acceleration. Then, outflow offluid from the airbag is controlled to provide for an adjustment of theinitial control based on the actual chest acceleration.

Outflow of fluid, most likely gas, from the airbag may be controlled byarranging an exit control valve or vent in, on or in connection with theairbag and which is adjustable to provide variable outflows of gas fromthe airbag.

Variations in the outflow may be made based on whether the occupant iswearing a seatbelt, which may be detected in any known manner, e.g., bymeans of a seatbelt buckle sensor.

Contact between the airbag and the occupant may be detected by analyzingdeceleration of the airbag. To this end, the sensor may be anaccelerometer arranged on a surface of the airbag to sense decelerationof the airbag. Alternatively, the sensor may be a pressure sensorarranged to sense the pressure in the airbag which is correlatable tothe deceleration of the airbag. In general, any pressure or forcemeasuring sensor may be arranged in connection with the airbag to sensea property of the airbag or a part thereof. The sensor can even beinternal to the airbag. For example, when the airbag includes one ormore tethers between opposed inner surfaces, the sensor can be arrangedto measure tension in the tether(s), e.g., on the tether itself.

A method for controlling deployment of a vehicular airbag in accordancewith the invention includes detecting an accident involving the vehicle,deploying the airbag toward an occupant prior to or during the accidentat initial deployment conditions, detecting contact between the airbagand the occupant by means of a sensor, determining adjusted deploymentconditions based on the detected contact, and adjusting the deploymentof the airbag to provide the adjusted deployment conditions. In oneembodiment, the initial deployment conditions are determined based onthe forecast severity of the accident. Additionally or alternatively,the adjusted deployment conditions can be determined based on whetherthe occupant is wearing the seatbelt. The same variations to the methoddescribed above can be implemented in this method as well.

A system for controlling outflow of fluid from a vehicular airbag inaccordance with the invention includes an airbag arranged to deploytoward an occupant prior to or during an accident involving the vehicle,a sensor system for detecting contact between the airbag and theoccupant, and a fluid outflow control system for controlling outflow offluid from the airbag based on the contact between the airbag and theoccupant as detected by the sensor system.

The control system may include an exit control valve or vent arranged inthe airbag.

The sensor system may be arranged to sense deceleration of the airbagwhereby analysis of the sensed deceleration provides an indication ofcontact between the airbag and the occupant. To this end, the sensorsystem can include an accelerometer arranged on a surface of the airbagfacing the occupant and which senses deceleration of the airbag. Thesensor system can also be arranged to sense pressure in the airbagwhereby analysis of the sensed pressure provides an indication ofcontact between the airbag and the occupant.

When airbag includes at least one tether between opposed inner surfaces,the sensor system can include at least one sensor arranged to measuretension in the tether or each tether, and from the tension, contactbetween the airbag and the occupant is detectable or determinable (sincea reduction in tension or elimination of tension may be indicative ofcontact between the airbag and the occupant). In this case, the controlsystem can include an exit control valve or vent arranged in connectionwith the airbag, or inflator, to vent fluid from the airbag and acontrol module coupled to the sensor(s) to control the exit controlvalve or vent.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of embodiments of the systemdeveloped or adapted using the teachings of at least one of theinventions disclosed herein and are not meant to limit the scope of theinvention as encompassed by the claims.

FIG. 1 is a side view with parts cutaway and removed of a vehicleshowing the passenger compartment containing a rear facing child seat onthe front passenger seat and a preferred mounting location for anoccupant and rear facing child seat presence detector including anantenna field sensor and a resonator or reflector placed onto theforward most portion of the child seat.

FIG. 2 is a side view with parts cutaway and removed showingschematically the interface between the vehicle interior monitoringsystem of at least one of the inventions disclosed herein and thevehicle cellular or other telematics communication system including anantenna field sensor.

FIG. 3 is a side view with parts cutaway and removed of a vehicleshowing the passenger compartment containing a box on the frontpassenger seat and a preferred mounting location for an occupant andrear facing child seat presence detector and including an antenna fieldsensor.

FIG. 4 is a side view with parts cutaway and removed of a vehicleshowing the passenger compartment containing a driver and a preferredmounting location for an occupant identification system and including anantenna field sensor and an inattentiveness response button.

FIG. 5 is a side view, with certain portions removed or cut away, of aportion of the passenger compartment of a vehicle showing severalpreferred mounting locations of occupant position sensors for sensingthe position of the vehicle driver.

FIG. 6 shows a seated-state detecting unit in accordance with thepresent invention and the connections between ultrasonic orelectromagnetic sensors, a weight sensor, a reclining angle detectingsensor, a seat track position detecting sensor, a heartbeat sensor, amotion sensor, a neural network, and an airbag system installed within avehicle compartment.

FIG. 6A is an illustration as in FIG. 6 with the replacement of a straingage weight sensor within a cavity within the seat cushion for thebladder weight sensor of FIG. 6.

FIG. 6B is a schematic showing the manner in which dynamic forces of thevehicle can be compensated for in a weight measurement of the occupant.

FIG. 7 is a perspective view of a vehicle showing the position of theultrasonic or electromagnetic sensors relative to the driver and frontpassenger seats.

FIG. 8A is a side planar view, with certain portions removed or cutaway, of a portion of the passenger compartment of a vehicle showingseveral preferred mounting locations of interior vehicle monitoringsensors shown particularly for sensing the vehicle driver illustratingthe wave pattern from a CCD or CMOS optical position sensor mountedalong the side of the driver or centered above his or her head.

FIG. 8B is a view as in FIG. 8A illustrating the wave pattern from anoptical system using an infrared light source and a CCD or CMOS arrayreceiver using the windshield as a reflection surface and showingschematically the interface between the vehicle interior monitoringsystem of at least one of the inventions disclosed herein and aninstrument panel mounted inattentiveness warning light or buzzer andreset button.

FIG. 8C is a view as in FIG. 8A illustrating the wave pattern from anoptical system using an infrared light source and a CCD or CMOS arrayreceiver where the CCD or CMOS array receiver is covered by a lenspermitting a wide angle view of the contents of the passengercompartment.

FIG. 8D is a view as in FIG. 8A illustrating the wave pattern from apair of small CCD or CMOS array receivers and one infrared transmitterwhere the spacing of the CCD or CMOS arrays permits an accuratemeasurement of the distance to features on the occupant.

FIG. 8E is a view as in FIG. 8A illustrating the wave pattern from a setof ultrasonic transmitter/receivers where the spacing of the transducersand the phase of the signal permits an accurate focusing of theultrasonic beam and thus the accurate measurement of a particular pointon the surface of the driver.

FIG. 9 is a circuit diagram of the seated-state detecting unit of thepresent invention.

FIGS. 10(a), 10(b) and 10(c) are each a diagram showing theconfiguration of the reflected waves of an ultrasonic wave transmittedfrom each transmitter of the ultrasonic sensors toward the passengerseat, obtained within the time that the reflected wave arrives at areceiver, FIG. 10(a) showing an example of the reflected waves obtainedwhen a passenger is in a normal seated-state, FIG. 10(b) showing anexample of the reflected waves obtained when a passenger is in anabnormal seated-state (where the passenger is seated too close to theinstrument panel), and FIG. 10(c) showing a transmit pulse.

FIG. 11 is a diagram of the data processing of the reflected waves fromthe ultrasonic or electromagnetic sensors.

FIG. 12 a flowchart showing the training steps of a neural network.

FIG. 13 a is an explanatory diagram of a process for normalizing thereflected wave and shows normalized reflected waves.

FIG. 13 b is a diagram similar to FIG. 13 a showing a step of extractingdata based on the normalized reflected waves and a step of weighting theextracted data by employing the data of the seat track positiondetecting sensor, the data of the reclining angle detecting sensor, andthe data of the weight sensor.

FIG. 14 is a perspective view of the interior of the passengercompartment of an automobile, with parts cut away and removed, showing avariety of transmitters that can be used in a phased array system.

FIG. 15 is a perspective view of a vehicle containing an adult occupantand an occupied infant seat on the front seat with the vehicle shown inphantom illustrating one preferred location of the transducers placedaccording to the methods taught in at least one of the inventionsdisclosed herein.

FIG. 16 is a schematic illustration of a system for controllingoperation of a vehicle or a component thereof based on recognition of anauthorized individual.

FIG. 17 is a schematic illustration of a method for controllingoperation of a vehicle based on recognition of an individual.

FIG. 18 is a perspective view of a seat shown in phantom, with a movableheadrest and sensors for measuring the height of the occupant from thevehicle seat, and a weight sensor shown mounted onto the seat.

FIG. 18A is a view taken along line 18A-18A in FIG. 18.

FIG. 18B is an enlarged view of the section designated 18B in FIG. 18.

FIG. 18C is a view of another embodiment of a seat with a weight sensorsimilar to the view shown in FIG. 18A.

FIG. 18D is a view of another embodiment of a seat with a weight sensorin which a SAW strain gage is placed on the bottom surface of thecushion.

FIG. 19 is a perspective view of a one embodiment of an apparatus formeasuring the weight of an occupying item of a seat illustrating weightsensing transducers mounted on a seat control mechanism portion which isattached directly to the seat.

FIG. 20 illustrates a seat structure with the seat cushion and backcushion removed illustrating a three-slide attachment of the seat to thevehicle and preferred mounting locations on the seat structure forstrain measuring weight sensors of an apparatus for measuring the weightof an occupying item of a seat in accordance with the invention.

FIG. 20A illustrates an alternate view of the seat structure transducermounting location taken in the circle 20A of FIG. 20 with the additionof a gusset and where the strain gage is mounted onto the gusset.

FIG. 20B illustrates a mounting location for a weight sensing transduceron a centralized transverse support member in an apparatus for measuringthe weight of an occupying item of a seat in accordance with theinvention.

FIGS. 21A, 21B and 21C illustrate three alternate methods of mountingstrain transducers of an apparatus for measuring the weight of anoccupying item of a seat in accordance with the invention onto a tubularseat support structural member.

FIG. 22 illustrates an alternate weight sensing transducer utilizingpressure sensitive transducers.

FIG. 22A illustrates a part of another alternate weight sensing systemfor a seat.

FIG. 23 illustrates an alternate seat structure assembly utilizingstrain transducers.

FIG. 23A is a perspective view of a cantilevered beam type load cell foruse with the weight measurement system of at least one of the inventionsdisclosed herein for mounting locations of FIG. 23, for example.

FIG. 23B is a perspective view of a simply supported beam type load cellfor use with the weight measurement system of at least one of theinventions disclosed herein as an alternate to the cantilevered loadcell of FIG. 23A.

FIG. 23C is an enlarged view of the portion designated 23C in FIG. 23B.

FIG. 23D is a perspective view of a tubular load cell for use with theweight measurement system of at least one of the inventions disclosedherein as an alternate to the cantilevered load cell of FIG. 23A.

FIG. 23E is a perspective view of a torsional beam load cell for usewith the weight measurement apparatus in accordance with the inventionas an alternate to the cantilevered load cell of FIG. 23A.

FIG. 24 is a perspective view of an automatic seat adjustment system,with the seat shown in phantom, with a movable headrest and sensors formeasuring the height of the occupant from the vehicle seat showingmotors for moving the seat and a control circuit connected to thesensors and motors.

FIG. 25 is a view of the seat of FIG. 24 showing a system for changingthe stiffness and the damping of the seat.

FIG. 25A is a view of the seat of FIG. 24 wherein the bladder contains aplurality of chambers.

FIG. 26 is a schematic drawing of one embodiment of an occupantrestraint device control system in accordance with the invention.

FIG. 27 is a flow chart of the operation of one embodiment of anoccupant restraint device control method in accordance with theinvention.

FIG. 28 is a view showing an inflated airbag and an arrangement forcontrolling both the flow of gas into and the flow of gas out of theairbag during the crash where the determination is made based on aheight sensor located in the headrest and a weight sensor in the seat.

FIG. 28A illustrates the valving system of FIG. 28.

FIGS. 29A and 29B are schematic drawings of basic embodiments of anadjustment system in accordance with the invention.

FIG. 30 is a flow chart of an arrangement for controlling a component inaccordance with the invention.

FIG. 31 is a side plan view of the interior of an automobile, withportions cut away and removed, with two occupant height measuringsensors, one mounted into the headliner above the occupant's head andthe other mounted onto the A-pillar and also showing a seatbeltassociated with the seat wherein the seatbelt has an adjustable upperanchorage point which is automatically adjusted based on the height ofthe occupant.

FIG. 32 is a view of the seat of FIG. 24 showing motors for changing thetilt of seat back and the lumbar support.

FIG. 33 is a view as in FIG. 31 showing a driver and driver seat with anautomatically adjustable steering column and pedal system which isadjusted based on the morphology of the driver.

FIG. 33A is a schematic showing the manner in which the steering columnis adjusted based on the morphology of the driver.

FIG. 33B is a view similar to FIG. 33 and shows the use of two motorsfor adjusting the position of the steering wheel.

FIG. 34 is a view similar to FIG. 24 showing the occupant's eyes and theseat adjusted to place the eyes at a particular vertical position forproper viewing through the windshield and rear view mirror.

FIG. 35 is a diagram of one exemplifying embodiment of the invention.

FIG. 36 is a schematic view of overall telematics system in accordancewith the invention.

FIG. 37 shows blocks of a Spice model of a transducer together withmedium and electrical circuits for ringing reduction.

FIG. 38 shows a circuit of the medium Spice model shown in FIG. 37.

FIG. 39 shows a circuit of the SourceTC/SourceTC_r Spice model shown inFIG. 37.

FIG. 40 shows an equivalent circuit of the transducer, which is taken asthe equivalent circuit of a piezoelectric resonator.

FIG. 41 shows a circuit of the Transducer (transmitting and receiving)Spice models shown in FIG. 37.

FIG. 42 shows a schematic of a non-linear circuit submitted foranalysis.

FIG. 43 shows a Spice model for the non-linear circuit shown in FIG. 42.

FIG. 44 shows an equivalent circuit of the transducer with a matchingcircuit.

FIG. 45 shows a schematic of a linear circuit Spice model.

FIG. 46 shows a schematic of the measurement apparatus used to test thelinear circuit shown in FIG. 45.

FIG. 47 is a circuit diagram of another embodiment of the inventionadditionally containing switching means for switching in and out of thereactive components.

FIG. 48 is a view of a transducer with a mechanical filter made fromplastic or rubber foam for reducing the audible clicking from thetransducer.

FIG. 49 is a schematic of an airbag with integrated sensors fordetermining contact between the airbag and an occupant.

DETAILED DESCRIPTION OF THE INVENTION

Note whenever a patent or literature is referred to below it is to beassumed that all of that patent or literature is to be incorporated byreference in its entirety to the extent the disclosure of thesereference is necessary. Also note that although many of the examplesbelow relate to a particular vehicle, an automobile, the invention isnot limited to any particular vehicle and is thus applicable to allrelevant vehicles including shipping containers and truck trailers andto all compartments of a vehicle including, for example, the passengercompartment and the trunk of an automobile or truck.

1. General Occupant Sensors

Referring to the accompanying drawings, FIG. 1 is a side view, withparts cutaway and removed of a vehicle showing the passengercompartment, or passenger container, containing a rear facing child seat2 on a front passenger seat 4 and a preferred mounting location for afirst embodiment of a vehicle interior monitoring system in accordancewith the invention. The interior monitoring system is capable ofdetecting the presence of an object, occupying objects such as a box, anoccupant or a rear facing child seat 2, determining the type of object,determining the location of the object, and/or determining anotherproperty or characteristic of the object. A property of the object couldbe the orientation of a child seat, the velocity of an adult and thelike. For example, the vehicle interior monitoring system can determinethat an object is present on the seat, that the object is a child seatand that the child seat is rear-facing. The vehicle interior monitoringsystem could also determine that the object is an adult, that he isdrunk and that he is out of position relative to the airbag.

In this embodiment, three transducers 6, 8 and 10 are used alone, or,alternately in combination with one or more antenna near fieldmonitoring sensors or transducers, 12, 14 and 16, although any number ofwave-transmitting transducers or radiation-receiving receivers may beused. Such transducers or receivers may be of the type that emit orreceive a continuous signal, a time varying signal or a spatial varyingsignal such as in a scanning system and each may comprise only atransmitter which transmits energy, waves or radiation, only a receiverwhich receives energy, waves or radiation, both a transmitter and areceiver capable of transmitting and receiving energy, waves orradiation, an electric field sensor, a capacitive sensor, or aself-tuning antenna-based sensor, weight sensor, chemical sensor, motionsensor or vibration sensor, for example.

One particular type of radiation-receiving receiver for use in theinvention receives electromagnetic waves and another receives ultrasonicwaves.

In an ultrasonic embodiment, transducer 8 can be used as a transmitterand transducers 6 and 10 can be used as receivers. Naturally, othercombinations can be used such as where all transducers are transceivers(transmitters and receivers). For example, transducer 8 can beconstructed to transmit ultrasonic energy toward the front passengerseat, which is modified, in this case by the occupying item of thepassenger seat, i.e., the rear facing child seat 2, and the modifiedwaves are received by the transducers 6 and 10, for example. A morecommon arrangement is where transducers 6, 8 and 10 are alltransceivers. Modification of the ultrasonic energy may constitutereflection of the ultrasonic energy as the ultrasonic energy isreflected back by the occupying item of the seat. The waves received bytransducers 6 and 10 vary with time depending on the shape of the objectoccupying the passenger seat, in this case the rear facing child seat 2.Each different occupying item will reflect back waves having a differentpattern. Also, the pattern of waves received by transducer 6 will differfrom the pattern received by transducer 10 in view of its differentmounting location. This difference generally permits the determinationof location of the reflecting surface (i.e., the rear facing child seat2) through triangulation. Through the use of two transducers 6, 10, asort of stereographic image is received by the two transducers andrecorded for analysis by processor 20, which is coupled to thetransducers 6, 8, 10, e.g., by wires or wirelessly. This image willdiffer for each object that is placed on the vehicle seat and it willalso change for each position of a particular object and for eachposition of the vehicle seat. Elements 6, 8, 10, although described astransducers, are representative of any type of component used in awave-based analysis technique. Also, although the example of anautomobile passenger compartment has been shown, the same principle canbe used for monitoring the interior of any vehicle including inparticular shipping containers and truck trailers.

Wave-type sensors as the transducers 6, 8, 10 as well as electric fieldsensors 12, 14, 16 are mentioned above. Electric field sensors and wavesensors are essentially the same from the point of view of sensing thepresence of an occupant in a vehicle. In both cases, a time varyingelectric field is disturbed or modified by the presence of the occupant.At high frequencies in the visual, infrared and high frequency radiowave region, the sensor is based on its capability to sense a change ofwave characteristics of the electromagnetic field, such as amplitude,phase or frequency. As the frequency drops, other characteristics of thefield are measured. At still lower frequencies, the occupant'sdielectric properties modify parameters of the reactive electric fieldin the occupied space between or near the plates of a capacitor. In thislatter case, the sensor senses the change in charge distribution on thecapacitor plates by measuring, for example, the current wave magnitudeor phase in the electric circuit that drives the capacitor. Thesemeasured parameters are directly connected with parameters of thedisplacement current in the occupied space. In all cases, the presenceof the occupant reflects, absorbs or modifies the waves or variations inthe electric field in the space occupied by the occupant. Thus, for thepurposes of at least one of the inventions disclosed herein,capacitance, electric field or electromagnetic wave sensors areequivalent and although they are all technically “field” sensors theywill be considered as “wave” sensors herein. What follows is adiscussion comparing the similarities and differences between two typesof field or wave sensors, electromagnetic wave sensors and capacitivesensors as exemplified by Kithil in U.S. Pat. No. 5,702,634.

An electromagnetic field disturbed or emitted by a passenger in the caseof an electromagnetic wave sensor, for example, and the electric fieldsensor of Kithil, for example, are in many ways similar and equivalentfor the purposes of at least one of the inventions disclosed herein. Theelectromagnetic wave sensor is an actual electromagnetic wave sensor bydefinition because they sense parameters of an electromagnetic wave,which is a coupled pair of continuously changing electric and magneticfields. The electric field here is not a static, potential one. It isessentially a dynamic, rotational electric field coupled with a changingmagnetic one, that is, an electromagnetic wave. It cannot be produced bya steady distribution of electric charges. It is initially produced bymoving electric charges in a transmitter, even if this transmitter is apassenger body for the case of a passive infrared sensor.

In the Kithil sensor, a static electric field is declared as an initialmaterial agent coupling a passenger and a sensor (see Column 5, lines5-7: “The proximity sensor 12 each function by creating an electrostaticfield between oscillator input loop 54 and detector output loop 56,which is affected by presence of a person near by, as a result ofcapacitive coupling, . . . ”). It is a potential, non-rotationalelectric field. It is not necessarily coupled with any magnetic field.It is the electric field of a capacitor. It can be produced with asteady distribution of electric charges. Thus, it is not anelectromagnetic wave by definition but if the sensor is driven by avarying current, then it produces a quasistatic electric field in thespace between/near the plates of the capacitor.

Kithil declares that his capacitance sensor uses a static electricfield. Thus, from the consideration above, one can conclude thatKithil's sensor cannot be treated as a wave sensor because there are noactual electromagnetic waves but only a static electric field of thecapacitor in the sensor system. However, this is not believed to be thecase. The Kithil system could not operate with a true static electricfield because a steady system does not carry any information. Therefore,Kithil is forced to use an oscillator, causing an alternate current inthe capacitor and a reactive quasi-static electric field in the spacebetween the capacitor plates, and a detector to reveal an informativechange of the sensor capacitance caused by the presence of an occupant(see FIG. 7 and its description). In this case, the system becomes a“wave sensor” in the sense that it starts generating an actualtime-varying electric field that certainly originates electromagneticwaves according to the definition above. That is, Kithil's sensor can betreated as a wave sensor regardless of the shape of the electric fieldthat it creates, a beam or a spread shape.

As follows from the Kithil patent, the capacitor sensor is likely aparametric system where the capacitance of the sensor is controlled bythe influence of the passenger body. This influence is transferred bymeans of the near electromagnetic field (i.e., the wave-like process)coupling the capacitor electrodes and the body. It is important to notethat the same influence takes place with a real static electric fieldalso, that is in absence of any wave phenomenon. This would be asituation if there were no oscillator in Kithil's system. However, sucha system is not workable and thus Kithil reverts to a dynamic systemusing time-varying electric fields.

Thus, although Kithil declares that the coupling is due to a staticelectric field, such a situation is not realized in his system becausean alternating electromagnetic field (“quasi-wave”) exists in the systemdue to the oscillator. Thus, his sensor is actually a wave sensor, thatis, it is sensitive to a change of a wave field in the vehiclecompartment. This change is measured by measuring the change of itscapacitance. The capacitance of the sensor system is determined by theconfiguration of its electrodes, one of which is a human body, that is,the passenger inside of and the part which controls the electrodeconfiguration and hence a sensor parameter, the capacitance.

The physics definition of “wave” from Webster's Encyclopedic UnabridgedDictionary is: “11. Physics. A progressive disturbance propagated frompoint to point in a medium or space without progress or advance of thepoints themselves, . . . ”. In a capacitor, the time that it takes forthe disturbance (a change in voltage) to propagate through space, thedielectric and to the opposite plate is generally small and neglectedbut it is not zero. As the frequency driving the capacitor increases andthe distance separating the plates increases, this transmission time asa percentage of the period of oscillation can become significant.Nevertheless, an observer between the plates will see the rise and fallof the electric field much like a person standing in the water of anocean. The presence of a dielectric body between the plates causes thewaves to get bigger as more electrons flow to and from the plates of thecapacitor. Thus, an occupant affects the magnitude of these waves whichis sensed by the capacitor circuit. Thus, the electromagnetic field is amaterial agent that carries information about a passenger's position inboth Kithil's and a beam-type electromagnetic wave sensor.

For ultrasonic systems, the “image” recorded from each ultrasonictransducer/receiver, is actually a time series of digitized data of theamplitude of the received signal versus time. Since there are tworeceivers, two time series are obtained which are processed by theprocessor 20. The processor 20 may include electronic circuitry andassociated, embedded software. Processor 20 constitutes one form ofgenerating means in accordance with the invention which generatesinformation about the occupancy of the passenger compartment based onthe waves received by the transducers 6, 8, 10.

When different objects are placed on the front passenger seat, theimages from transducers 6, 8, 10 for example, are different but thereare also similarities between all images of rear facing child seats, forexample, regardless of where on the vehicle seat it is placed andregardless of what company manufactured the child seat. Alternately,there will be similarities between all images of people sitting on theseat regardless of what they are wearing, their age or size. The problemis to find the “rules” which differentiate the images of one type ofobject from the images of other types of objects, e.g., whichdifferentiate the occupant images from the rear facing child seatimages. The similarities of these images for various child seats arefrequently not obvious to a person looking at plots of the time seriesand thus computer algorithms are developed to sort out the variouspatterns. For a more detailed discussion of pattern recognition see USRE 37260 to Varga et al.

The determination of these rules is important to the pattern recognitiontechniques used in at least one of the inventions disclosed herein. Ingeneral, three approaches have been useful, artificial intelligence,fuzzy logic and artificial neural networks (including cellular andmodular or combination neural networks and support vectormachines—although additional types of pattern recognition techniques mayalso be used, such as sensor fusion). In some implementations of atleast one of the inventions disclosed herein, such as the determinationthat there is an object in the path of a closing window as describedbelow, the rules are sufficiently obvious that a trained researcher cansometimes look at the returned signals and devise a simple algorithm tomake the required determinations. In others, such as the determinationof the presence of a rear facing child seat or of an occupant,artificial neural networks can be used to determine the rules. One suchset of neural network software for determining the pattern recognitionrules is available from the International Scientific Research, Inc. ofPanama City, Panama.

Electromagnetic energy based occupant sensors exist that use manyportions of the electromagnetic spectrum. A system based on theultraviolet, visible or infrared portions of the spectrum generallyoperate with a transmitter and a receiver of reflected radiation. Thereceiver may be a camera or a photo detector such as a pin or avalanchediode as described in detail in above-referenced patents and patentapplications. At other frequencies, the absorption of theelectromagnetic energy is primarily used and at still other frequenciesthe capacitance or electric field influencing effects are used.Generally, the human body will reflect, scatter, absorb or transmitelectromagnetic energy in various degrees depending on the frequency ofthe electromagnetic waves. All such occupant sensors are includedherein.

In an embodiment wherein electromagnetic energy is used, it is to beappreciated that any portion of the electromagnetic signals thatimpinges upon, surrounds or involves a body portion of the occupant isat least partially absorbed by the body portion. Sometimes, this is dueto the fact that the human body is composed primarily of water, and thatelectromagnetic energy of certain frequencies is readily absorbed bywater. The amount of electromagnetic signal absorption is related to thefrequency of the signal, and size or bulk of the body portion that thesignal impinges upon. For example, a torso of a human body tends toabsorb a greater percentage of electromagnetic energy than a hand of ahuman body.

Thus, when electromagnetic waves or energy signals are transmitted by atransmitter, the returning waves received by a receiver provide anindication of the absorption of the electromagnetic energy. That is,absorption of electromagnetic energy will vary depending on the presenceor absence of a human occupant, the occupant's size, bulk, surfacereflectivity, etc. depending on the frequency, so that different signalswill be received relating to the degree or extent of absorption by theoccupying item on the seat. The receiver will produce a signalrepresentative of the returned waves or energy signals which will thusconstitute an absorption signal as it corresponds to the absorption ofelectromagnetic energy by the occupying item in the seat.

One or more of the transducers 6, 8, 10 can also be image-receivingdevices, such as cameras, which take images of the interior of thepassenger compartment. These images can be transmitted to a remotefacility to monitor the passenger compartment or can be stored in amemory device for use in the event of an accident, i.e., to determinethe status of the occupant(s) of the vehicle prior to the accident. Inthis manner, it can be ascertained whether the driver was fallingasleep, talking on the phone, etc.

A memory device for storing images of the passenger compartment, andalso for receiving and storing any other information, parameters andvariables relating to the vehicle or occupancy of the vehicle, may be inthe form a standardized “black box” (instead of or in addition to amemory part in a processor 20). The IEEE Standards Association iscurrently beginning to develop an international standard for motorvehicle event data recorders. The information stored in the black boxand/or memory unit in the processor 20, can include the images of theinterior of the passenger compartment as well as the number of occupantsand the health state of the occupant(s). The black box would preferablybe tamper-proof and crash-proof and enable retrieval of the informationafter a crash.

Transducer 8 can also be a source of electromagnetic radiation, such asan LED, and transducers 6 and 10 can be CMOS, CCD imagers or otherdevices sensitive to electromagnetic radiation or fields. This “image”or return signal will differ for each object that is placed on thevehicle seat, or elsewhere in the vehicle, and it will also change foreach position of a particular object and for each position of thevehicle seat or other movable objects within the vehicle. Elements 6, 8,10, although described as transducers, are representative of any type ofcomponent used in a wave-based or electric field analysis technique,including, e.g., a transmitter, receiver, antenna or a capacitor plate.

Transducers 12, 14 and 16 can be antennas placed in the seat andinstrument panel, or other convenient location within the vehicle, suchthat the presence of an object, particularly a water-containing objectsuch as a human, disturbs the near field of the antenna. Thisdisturbance can be detected by various means such as with Micrel partsMICREF102 and MICREF104, which have a built-in antenna auto-tunecircuit. Note, these parts cannot be used as is and it is necessary toredesign the chips to allow the auto-tune information to be retrievedfrom the chip.

Other types of transducers can be used along with the transducers 6, 8,10 or separately and all are contemplated by at least one of theinventions disclosed herein. Such transducers include other wave devicessuch as radar or electronic field sensing systems such as described inU.S. Pat. No. 5,366,241, U.S. Pat. No. 5,602,734, U.S. Pat. No.5,691,693, U.S. Pat. No. 5,802,479, U.S. Pat. No. 5,844,486, U.S. Pat.No. 6,014,602, and U.S. Pat. No. 6,275,146 to Kithil, and U.S. Pat. No.5,948,031 to Rittmueller. Another technology, for example, uses the factthat the content of the near field of an antenna affects the resonanttuning of the antenna. Examples of such a device are shown as antennas12, 14 and 16 in FIG. 1. By going to lower frequencies, the near fieldrange is increased and also at such lower frequencies, a ferrite-typeantenna could be used to minimize the size of the antenna. Otherantennas that may be applicable for a particular implementation includedipole, microstrip, patch, Yagi etc. The frequency transmitted by theantenna can be swept and the (VSWR) voltage and current in the antennafeed circuit can be measured. Classification by frequency domain is thenpossible. That is, if the circuit is tuned by the antenna, the frequencycan be measured to determine the object in the field.

An alternate system is shown in FIG. 2, which is a side view showingschematically the interface between the vehicle interior monitoringsystem of at least one of the inventions disclosed herein and thevehicle cellular or other communication system 32, such as a satellitebased system such as that supplied by Skybitz, having an associatedantenna 34. In this view, an adult occupant 30 is shown sitting on thefront passenger seat 4 and two transducers 6 and 8 are used to determinethe presence (or absence) of the occupant on that seat 4. One of thetransducers 8 in this case acts as both a transmitter and receiver whilethe other transducer 6 acts only as a receiver. Alternately, transducer6 could serve as both a transmitter and receiver or the transmittingfunction could be alternated between the two devices. Also, in manycases, more that two transmitters and receivers are used and in stillother cases, other types of sensors, such as weight, chemical,radiation, vibration, acoustic, seatbelt tension sensor or switch,heartbeat, self tuning antennas (12, 14), motion and seat and seatbackposition sensors, are also used alone or in combination with thetransducers 6 and 8. As is also the case in FIG. 1, the transducers 6and 8 are attached to the vehicle embedded in the A-pillar and headlinertrim, where their presence is disguised, and are connected to processor20 that may also be hidden in the trim as shown or elsewhere. Naturally,other mounting locations can also be used and, in most cases, preferredas disclosed in Varga et. al. (US RE 37260).

The transducers 6 and 8 in conjunction with the pattern recognitionhardware and software described below enable the determination of thepresence of an occupant within a short time after the vehicle isstarted. The software is implemented in processor 20 and is packaged ona printed circuit board or flex circuit along with the transducers 6 and8. Similar systems can be located to monitor the remaining seats in thevehicle, also determine the presence of occupants at the other seatinglocations and this result is stored in the computer memory, which ispart of each monitoring system processor 20. Processor 20 thus enables acount of the number of occupants in the vehicle to be obtained byaddition of the determined presence of occupants by the transducersassociated with each seating location, and in fact, can be designed toperform such an addition. Naturally, the principles illustrated forautomobile vehicles are applicable by those skilled in the art to othervehicles such as shipping containers or truck trailers and to othercompartments of an automotive vehicle such as the vehicle trunk.

For a general object, transducers 6, 8, 9, 10 can also be used todetermine the type of object, determine the location of the object,and/or determine another property or characteristic of the object. Aproperty of the object could be the orientation of a child seat, thevelocity of an adult and the like. For example, the transducers 6, 8, 9,10 can be designed to enable a determination that an object is presenton the seat, that the object is a child seat and that the child seat isrear-facing.

The transducers 6 and 8 are attached to the vehicle buried in the trimsuch as the A-pillar trim, where their presence can be disguised, andare connected to processor 20 that may also be hidden in the trim asshown (this being a non-limiting position for the processor 20). TheA-pillar is the roof support pillar that is closest to the front of thevehicle and which, in addition to supporting the roof, also supports thefront windshield and the front door. Other mounting locations can alsobe used. For example, transducers 6, 8 can be mounted inside the seat(along with or in place of transducers 12 and 14), in the ceiling of thevehicle, in the B-pillar, in the C-pillar and in the doors. Indeed, thevehicle interior monitoring system in accordance with the invention maycomprise a plurality of monitoring units, each arranged to monitor aparticular seating location. In this case, for the rear seatinglocations, transducers might be mounted in the B-pillar or C-pillar orin the rear of the front seat or in the rear side doors. Possiblemounting locations for transducers, transmitters, receivers and otheroccupant sensing devices are disclosed in the above-referenced patentapplications and all of these mounting locations are contemplated foruse with the transducers described herein.

The cellular phone or other communications system 32 outputs to anantenna 34. The transducers 6, 8, 12 and 14 in conjunction with thepattern recognition hardware and software, which is implemented inprocessor 20 and is packaged on a printed circuit board or flex circuitalong with the transducers 6 and 8, determine the presence of anoccupant within a few seconds after the vehicle is started, or within afew seconds after the door is closed. Similar systems located to monitorthe remaining seats in the vehicle, also determine the presence ofoccupants at the other seating locations and this result is stored inthe computer memory which is part of each monitoring system processor20.

Periodically and in particular in the event of an accident, theelectronic system associated with the cellular phone system 32interrogates the various interior monitoring system memories and arrivesat a count of the number of occupants in the vehicle, and optionally,even makes a determination as to whether each occupant was wearing aseatbelt and if he or she is moving after the accident. The phone orother communications system then automatically dials the EMS operator(such as 911 or through a telematics service such as OnStar®) and theinformation obtained from the interior monitoring systems is forwardedso that a determination can be made as to the number of ambulances andother equipment to send to the accident site, for example. Such vehicleswill also have a system, such as the global positioning system, whichpermits the vehicle to determine its exact location and to forward thisinformation to the EMS operator. Other systems can be implemented inconjunction with the communication with the emergency services operator.For example, a microphone and speaker can be activated to permit theoperator to attempt to communicate with the vehicle occupant(s) andthereby learn directly of the status and seriousness of the condition ofthe occupant(s) after the accident.

Thus, in basic embodiments of the invention, wave or otherenergy-receiving transducers are arranged in the vehicle at appropriatelocations, trained if necessary depending on the particular embodiment,and function to determine whether a life form is present in the vehicleand if so, how many life forms are present and where they are locatedetc. To this end, transducers can be arranged to be operative at only asingle seating location or at multiple seating locations with aprovision being made to eliminate a repetitive count of occupants. Adetermination can also be made using the transducers as to whether thelife forms are humans, or more specifically, adults, child in childseats, etc. As noted herein, this is possible using pattern recognitiontechniques. Moreover, the processor or processors associated with thetransducers can be trained to determine the location of the life forms,either periodically or continuously or possibly only immediately before,during and after a crash. The location of the life forms can be asgeneral or as specific as necessary depending on the systemrequirements, i.e., a determination can be made that a human is situatedon the driver's seat in a normal position (general) or a determinationcan be made that a human is situated on the driver's seat and is leaningforward and/or to the side at a specific angle as well as the positionof his or her extremities and head and chest (specifically). The degreeof detail is limited by several factors, including, for example, thenumber and position of transducers and training of the patternrecognition algorithm(s).

In addition to the use of transducers to determine the presence andlocation of occupants in a vehicle, other sensors could also be used.For example, a heartbeat sensor which determines the number and presenceof heartbeat signals can also be arranged in the vehicle, which wouldthus also determine the number of occupants as the number of occupantswould be equal to the number of heartbeat signals detected. Conventionalheartbeat sensors can be adapted to differentiate between a heartbeat ofan adult, a heartbeat of a child and a heartbeat of an animal. As itsname implies, a heartbeat sensor detects a heartbeat, and the magnitudeand/or frequency thereof, of a human occupant of the seat, if such ahuman occupant is present. The output of the heartbeat sensor is inputto the processor of the interior monitoring system. One heartbeat sensorfor use in the invention may be of the types as disclosed in McEwan(U.S. Pat. No. 5,573,012 and U.S. Pat. No. 5,766,208). The heartbeatsensor can be positioned at any convenient position relative to theseats where occupancy is being monitored. A preferred location is withinthe vehicle seatback.

An alternative way to determine the number of occupants is to monitorthe weight being applied to the seats, i.e., each seating location, byarranging weight sensors at each seating location which might also beable to provide a weight distribution of an object on the seat. Analysisof the weight and/or weight distribution by a predetermined method canprovide an indication of occupancy by a human, an adult or child, or aninanimate object.

Another type of sensor which is not believed to have been used in aninterior monitoring system previously is a micropower impulse radar(MIR) sensor which determines motion of an occupant and thus candetermine his or her heartbeat (as evidenced by motion of the chest).Such an MIR sensor can be arranged to detect motion in a particular areain which the occupant's chest would most likely be situated or could becoupled to an arrangement which determines the location of theoccupant's chest and then adjusts the operational field of the MIRsensor based on the determined location of the occupant's chest. Amotion sensor utilizing a micro-power impulse radar (MIR) system asdisclosed, for example, in McEwan (U.S. Pat. No. 5,361,070), as well asmany other patents by the same inventor.

Motion sensing is accomplished by monitoring a particular range from thesensor as disclosed in that patent. MIR is one form of radar which hasapplicability to occupant sensing and can be mounted at variouslocations in the vehicle. It has an advantage over ultrasonic sensors inthat data can be acquired at a higher speed and thus the motion of anoccupant can be more easily tracked. The ability to obtain returns overthe entire occupancy range is somewhat more difficult than withultrasound resulting in a more expensive system overall. MIR hasadditional advantages in lack of sensitivity to temperature variationand has a comparable resolution to about 40 kHz ultrasound. Resolutioncomparable to higher frequency ultrasound is also possible.Additionally, multiple MIR sensors can be used when high speed trackingof the motion of an occupant during a crash is required since they canbe individually pulsed without interfering with each through timedivision multiplexing.

An alternative way to determine motion of the occupant(s) is to monitorthe weight distribution of the occupant whereby changes in weightdistribution after an accident would be highly suggestive of movement ofthe occupant. A system for determining the weight distribution of theoccupants could be integrated or otherwise arranged in the seats such asthe front seat 4 of the vehicle and several patents and publicationsdescribe such systems.

More generally, any sensor which determines the presence and healthstate of an occupant can also be integrated into the vehicle interiormonitoring system in accordance with the invention. For example, asensitive motion sensor can determine whether an occupant is breathingand a chemical sensor can determine the amount of carbon dioxide, or theconcentration of carbon dioxide, in the air in the passenger compartmentof the vehicle which can be correlated to the health state of theoccupant(s). The motion sensor and chemical sensor can be designed tohave a fixed operational field situated where the occupant's mouth ismost likely to be located. In this manner, detection of carbon dioxidein the fixed operational field could be used as an indication of thepresence of a human occupant in order to enable the determination of thenumber of occupants in the vehicle. In the alternative, the motionsensor and chemical sensor can be adjustable and adapted to adjust theiroperational field in conjunction with a determination by an occupantposition and location sensor which would determine the location ofspecific parts of the occupant's body, e.g., his or her chest or mouth.Furthermore, an occupant position and location sensor can be used todetermine the location of the occupant's eyes and determine whether theoccupant is conscious, i.e., whether his or her eyes are open or closedor moving.

The use of chemical sensors can also be used to detect whether there isblood present in the vehicle, for example, after an accident.Additionally, microphones can detect whether there is noise in thevehicle caused by groaning, yelling, etc., and transmit any such noisethrough the cellular or other communication connection to a remotelistening facility (such as operated by OnStar®).

In FIG. 3, a view of the system of FIG. 1 is illustrated with a box 28shown on the front passenger seat in place of a rear facing child seat.The vehicle interior monitoring system is trained to recognize that thisbox 28 is neither a rear facing child seat nor an occupant and thereforeit is treated as an empty seat and the deployment of the airbag or otheroccupant restraint device is suppressed. For other vehicles, it may bethat just the presence of a box or its motion or chemical or radiationeffluents that are desired to be monitored. The auto-tune antenna-basedsystem 12, 14 is particularly adept at making this distinctionparticularly if the box 28 does not contain substantial amounts ofwater. Although a simple implementation of the auto-tune antenna systemis illustrated, it is of course possible to use multiple antennaslocated in the seat 4 and elsewhere in the passenger compartment andthese antenna systems can either operate at one or a multiple ofdifferent frequencies to discriminate type, location and/or relativesize of the object being investigated. This training can be accomplishedusing a neural network or modular neural network with the commerciallyavailable software. The system assesses the probability that the box 28is a person, however, and if there is even the remotest chance that itis a person, the airbag deployment is not suppressed. The system is thustypically biased toward enabling airbag deployment.

In cases where different levels of airbag inflation are possible, andthere are different levels of injury associated with an out of positionoccupant being subjected to varying levels of airbag deployment, it issometimes possible to permit a depowered or low level airbag deploymentin cases of uncertainty. If, for example, the neural network has aproblem distinguishing whether a box or a forward facing child seat ispresent on the vehicle seat, the decision can be made to deploy theairbag in a depowered or low level deployment state. Other situationswhere such a decision could be made would be when there is confusion asto whether a forward facing human is in position or out-of-position.

Neural networks systems frequently have problems in accuratelydiscriminating the exact location of an occupant especially whendifferent-sized occupants are considered. This results in a gray zonearound the border of the keep out zone where the system provides a weakfire or weak no fire decision. For those cases, deployment of the airbagin a depowered state can resolve the situation since an occupant in agray zone around the keep out zone boundary would be unlikely to beinjured by such a depowered deployment while significant airbagprotection is still being supplied.

Electromagnetic or ultrasonic energy can be transmitted in three modesin determining the position of an occupant, for example. In most of thecases disclosed above, it is assumed that the energy will be transmittedin a broad diverging beam which interacts with a substantial portion ofthe occupant or other object to be monitored. This method can have thedisadvantage that it will reflect first off the nearest object and,especially if that object is close to the transmitter, it may mask thetrue position of the occupant or object. It can also reflect off manyparts of the object where the reflections can be separated in time andprocessed as in an ultrasonic occupant sensing system. This can also bepartially overcome through the use of the second mode which uses anarrow beam. In this case, several narrow beams are used. These beamsare aimed in different directions toward the occupant from a positionsufficiently away from the occupant or object such that interference isunlikely.

A single receptor could be used provided the beams are either cycled onat different times or are of different frequencies. Another approach isto use a single beam emanating from a location which has an unimpededview of the occupant or object such as the windshield header in the caseof an automobile or near the roof at one end of a trailer or shippingcontainer, for example. If two spaced apart CCD array receivers areused, the angle of the reflected beam can be determined and the locationof the occupant can be calculated. The third mode is to use a singlebeam in a manner so that it scans back and forth and/or up and down, orin some other pattern, across the occupant, object or the space ingeneral. In this manner, an image of the occupant or object can beobtained using a single receptor and pattern recognition software can beused to locate the head or chest of the occupant or size of the object,for example. The beam approach is most applicable to electromagneticenergy but high frequency ultrasound can also be formed into a narrowbeam.

A similar effect to modifying the wave transmission mode can also beobtained by varying the characteristics of the receptors. Throughappropriate lenses or reflectors, receptors can be made to be mostsensitive to radiation emitted from a particular direction. In thismanner, a single broad beam transmitter can be used coupled with anarray of focused receivers, or a scanning receiver, to obtain a roughimage of the occupant or occupying object.

Each of these methods of transmission or reception could be used, forexample, at any of the preferred mounting locations shown in FIG. 5.

As shown in FIG. 7, there are provided four sets of wave-receivingsensor systems 6, 8, 9, 10 mounted within the passenger compartment ofan automotive vehicle. Each set of sensor systems 6, 8, 9, 10 comprisesa transmitter and a receiver (or just a receiver in some cases), whichmay be integrated into a single unit or individual components separatedfrom one another. In this embodiment, the sensor system 6 is mounted onthe A-Pillar of the vehicle. The sensor system 9 is mounted on the upperportion of the B-Pillar. The sensor system 8 is mounted on the roofceiling portion or the headliner. The sensor system 10 is mounted nearthe middle of an instrument panel 17 in front of the driver's seat 3.

The sensor systems 6, 8, 9, 10 are preferably ultrasonic orelectromagnetic, although sensor systems 6, 8, 9, 10 can be any othertype of sensors which will detect the presence of an occupant from adistance including capacitive or electric field sensors. Also, if thesensor systems 6, 8, 9, 10 are passive infrared sensors, for example,then they may only comprise a wave-receiver. Recent advances in QuantumWell Infrared Photodetectors by NASA show great promise for thisapplication. See “Many Applications Possible For Largest QuantumInfrared Detector”, Goddard Space Center News Release Feb. 27, 2002.

The Quantum Well Infrared Photodetector is a new detector which promisesto be a low-cost alternative to conventional infrared detectortechnology for a wide range of scientific and commercial applications,and particularly for sensing inside and outside of a vehicle. The mainproblem that needs to be solved is that it operates at 76 degrees Kelvin(−323 degrees F.). Chips are being developed capable of cooling otherchips economically. It remains to be seen if these low temperatures canbe economically achieved.

A section of the passenger compartment of an automobile is showngenerally as 40 in FIGS. 8A-8D. A driver 30 of the vehicle sits on aseat 3 behind a steering wheel 42, which contains an airbag assembly 44.Airbag assembly 44 may be integrated into the steering wheel assembly orcoupled to the steering wheel 42. Five transmitter and/or receiverassemblies 49, 50, 51, 52 and 54 are positioned at various places in thepassenger compartment to determine the location of various parts of thedriver, e.g., the head, chest and torso, relative to the airbag and tootherwise monitor the interior of the passenger compartment. Monitoringof the interior of the passenger compartment can entail detecting thepresence or absence of the driver and passengers, differentiatingbetween animate and inanimate objects, detecting the presence ofoccupied or unoccupied child seats, rear-facing or forward-facing, andidentifying and ascertaining the identity of the occupying items in thepassenger compartment. Naturally, a similar system can be used formonitoring the interior of a truck, shipping container or othercontainers.

A processor such as control circuitry 20 is connected to thetransmitter/receiver assemblies 49, 50, 51, 52, 54 and controls thetransmission from the transmitters, if a transmission component ispresent in the assemblies, and captures the return signals from thereceivers, if a receiver component is present in the assemblies. Controlcircuitry 20 usually contains analog to digital converters (ADCs) or aframe grabber or equivalent, a microprocessor containing sufficientmemory and appropriate software including, for example, patternrecognition algorithms, and other appropriate drivers, signalconditioners, signal generators, etc. Usually, in any givenimplementation, only three or four of the transmitter/receiverassemblies would be used depending on their mounting locations asdescribed below. In some special cases, such as for a simpleclassification system, only a single or sometimes only twotransmitter/receiver assemblies are used.

A portion of the connection between the transmitter/receiver assemblies49, 50, 51, 52, 54 and the control circuitry 20, is shown as wires.These connections can be wires, either individual wires leading from thecontrol circuitry 20 to each of the transmitter/receiver assemblies 49,50, 51, 52, 54 or one or more wire buses or in some cases, wireless datatransmission can be used.

The location of the control circuitry 20 in the dashboard of the vehicleis for illustration purposes only and does not limit the location of thecontrol circuitry 20. Rather, the control circuitry 20 may be locatedanywhere convenient or desired in the vehicle.

It is contemplated that a system and method in accordance with theinvention can include a single transmitter and multiple receivers, eachat a different location. Thus, each receiver would not be associatedwith a transmitter forming transmitter/receiver assemblies. Rather, forexample, with reference to FIG. 8A, only element 51 could constitute atransmitter/receiver assembly and elements 49, 50, 52 and 54 could bereceivers only.

On the other hand, it is conceivable that in some implementations, asystem and method in accordance with the invention include a singlereceiver and multiple transmitters. Thus, each transmitter would not beassociated with a receiver forming transmitter/receiver assemblies.Rather, for example, with reference to FIG. 8A, only element 51 wouldconstitute a transmitter/receiver assembly and elements 49, 50, 52, 54would be transmitters only.

One ultrasonic transmitter/receiver as used herein is similar to thatused on modern auto-focus cameras such as manufactured by the PolaroidCorporation. Other camera auto-focusing systems use differenttechnologies, which are also applicable here, to achieve the samedistance to object determination. One camera system manufactured by Fujiof Japan, for example, uses a stereoscopic system which could also beused to determine the position of a vehicle occupant providing there issufficient light available. In the case of insufficient light, a sourceof infrared light can be added to illuminate the driver. In a relatedimplementation, a source of infrared light is reflected off of thewindshield and illuminates the vehicle occupant. An infrared receiver 56is located attached to the rear view mirror assembly 55, as shown inFIG. 8E. Alternately, the infrared can be sent by the device 50 andreceived by a receiver elsewhere. Since any of the devices shown inthese figures could be either transmitters or receivers or both, forsimplicity, only the transmitted and not the reflected wave fronts arefrequently illustrated.

When using the surface of the windshield as a reflector of infraredradiation (for transmitter/receiver assembly and element 52), care mustbe taken to assure that the desired reflectivity at the frequency ofinterest is achieved. Mirror materials, such as metals and other specialmaterials manufactured by Eastman Kodak, have a reflectivity forinfrared frequencies that is substantially higher than at visiblefrequencies. They are thus candidates for coatings to be placed on thewindshield surfaces for this purpose.

There are two preferred methods of implementing the vehicle interiormonitoring system of at least one of the inventions disclosed herein, amicroprocessor system and an application specific integrated circuitsystem (ASIC). Both of these systems are represented schematically as 20herein. In some systems, both a microprocessor and an ASIC are used. Inother systems, most if not all of the circuitry is combined onto asingle chip (system on a chip). The particular implementation depends onthe quantity to be made and economic considerations.

1.1 Ultrasonics

1.1.1 General

The maximum acoustic frequency that is practical to use for acousticimaging in the systems is about 40 to 160 kilohertz (kHz). Thewavelength of a 50 kHz acoustic wave is about 0.6 cm which is too coarseto determine the fine features of a person's face, for example. It iswell understood by those skilled in the art that features which are muchsmaller than the wavelength of the irradiating radiation cannot bedistinguished. Similarly, the wavelength of common radar systems variesfrom about 0.9 cm (for 33 GHz K band) to 133 cm (for 225 MHz P band)which are also too coarse for person-identification systems.

Referring now to FIG. 5, a section of the passenger compartment of anautomobile is shown generally as 40 in FIG. 5. A driver of a vehicle 30sits on a seat 3 behind a steering wheel 42 which contains an airbagassembly 44. Four transmitter and/or receiver assemblies 50, 52, 53 and54 are positioned at various places in or around the passengercompartment to determine the location of the head, chest and torso ofthe driver 30 relative to the airbag assembly 44. Usually, in any givenimplementation, only one or two of the transmitters and receivers wouldbe used depending on their mounting locations as described below.

FIG. 5 illustrates several of the possible locations of such devices.For example, transmitter and receiver 50 emits ultrasonic acousticalwaves which bounce off the chest of the driver 30 and return.Periodically, a burst of ultrasonic waves at about 50 kilohertz isemitted by the transmitter/receiver and then the echo, or reflectedsignal, is detected by the same or different device. An associatedelectronic circuit measures the time between the transmission and thereception of the ultrasonic waves and determines the distance from thetransmitter/receiver to the driver 30 based on the velocity of sound.This information can then be sent to a microprocessor that can belocated in the crash sensor and diagnostic circuitry which determines ifthe driver 30 is close enough to the airbag assembly 44 that adeployment might, by itself, cause injury to the driver 30. In such acase, the circuit disables the airbag system and thereby prevents itsdeployment. In an alternate case, the sensor algorithm assesses theprobability that a crash requiring an airbag is in process and waitsuntil that probability exceeds an amount that is dependent on theposition of the driver 30. Thus, for example, the sensor might decide todeploy the airbag based on a need probability assessment of 50%, if thedecision must be made immediately for a driver 30 approaching theairbag, but might wait until the probability rises to 95% for a moredistant driver. Although a driver system has been illustrated, thepassenger system would be similar.

Alternate mountings for the transmitter/receiver include variouslocations on the instrument panel on either side of the steering columnsuch as 53 in FIG. 5. Also, although some of the devices hereinillustrated assume that for the ultrasonic system, the same device isused for both transmitting and receiving waves, there are advantages inseparating these functions, at least for standard transducer systems.Since there is a time lag required for the system to stabilize aftertransmitting a pulse before it can receive a pulse, close measurementsare enhanced, for example, by using separate transmitters and receivers.In addition, if the ultrasonic transmitter and receiver are separated,the transmitter can transmit continuously, provided the transmittedsignal is modulated such that the received signal can be compared withthe transmitted signal to determine the time it takes for the waves toreach and reflect off of the occupant.

Many methods exist for this modulation including varying the frequencyor amplitude of the waves or pulse modulation or coding. In all cases,the logic circuit which controls the sensor and receiver must be able todetermine when the signal which was most recently received wastransmitted. In this manner, even though the time that it takes for thesignal to travel from the transmitter to the receiver, via reflectionoff of the occupant or other object to be monitored, may be severalmilliseconds, information as to the position of the occupant is receivedcontinuously which permits an accurate, although delayed, determinationof the occupant's velocity from successive position measurements. Othermodulation methods that may be applied to electromagnetic radiationsinclude TDMA, CDMA, noise or pseudo-noise, spatial, etc.

Conventional ultrasonic distance measuring devices must wait for thesignal to travel to the occupant or other monitored object and returnbefore a new signal is sent. This greatly limits the frequency at whichposition data can be obtained to the formula where the frequency isequal to the velocity of sound divided by two times the distance to theoccupant. For example, if the velocity of sound is taken at about 1000feet per second, occupant position data for an occupant or objectlocated one foot from the transmitter can only be obtained every 2milliseconds which corresponds to a frequency of about 500 Hz. At athree-foot displacement and allowing for some processing time, thefrequency is closer to about 100 Hz.

This slow frequency that data can be collected seriously degrades theaccuracy of the velocity calculation. The reflection of ultrasonic wavesfrom the clothes of an occupant or the existence of thermal gradients,for example, can cause noise or scatter in the position measurement andlead to significant inaccuracies in a given measurement. When manymeasurements are taken more rapidly, as in the technique described here,these inaccuracies can be averaged and a significant improvement in theaccuracy of the velocity calculation results.

The determination of the velocity of the occupant need not be derivedfrom successive distance measurements. A potentially more accuratemethod is to make use of the Doppler Effect where the frequency of thereflected waves differs from the transmitted waves by an amount which isproportional to the occupant's velocity. In one embodiment, a singleultrasonic transmitter and a separate receiver are used to measure theposition of the occupant, by the travel time of a known signal, and thevelocity, by the frequency shift of that signal. Although the DopplerEffect has been used to determine whether an occupant has fallen asleep,it has not previously been used in conjunction with a position measuringdevice to determine whether an occupant is likely to become out ofposition, i.e., an extrapolated position in the future based on theoccupant's current position and velocity as determined from successiveposition measurements, and thus in danger of being injured by adeploying airbag, or that a monitored object is moving. This combinationis particularly advantageous since both measurements can be accuratelyand efficiently determined using a single transmitter and receiver pairresulting in a low cost system.

One problem with Doppler measurements is the slight change in frequencythat occurs during normal occupant velocities. This requires thatsophisticated electronic techniques and a low Q receiver should beutilized to increase the frequency and thereby render it easier tomeasure the velocity using the phase shift. For many implementations,therefore, the velocity of the occupant is determined by calculating thedifference between successive position measurements.

The following discussion will apply to the case where ultrasonic sensorsare used although a similar discussion can be presented relative to theuse of electromagnetic sensors such as active infrared sensors, takinginto account the differences in the technologies. Also, the followingdiscussion will relate to an embodiment wherein the seat is the frontpassenger seat, although a similar discussion can apply to othervehicles and monitoring situations.

The ultrasonic or electromagnetic sensor systems, 6, 8, 9 and 10 in FIG.7 can be controlled or driven, one at a time or simultaneously, by anappropriate driver circuit such as ultrasonic or electromagnetic sensordriver circuit 58 shown in FIG. 9. The transmitters of the ultrasonic orelectromagnetic sensor systems 6, 8, 9 and 10 transmit respectiveultrasonic or electromagnetic waves toward the seat 4 and transmitpulses (see FIG. 10(c)) in sequence at times t1, t2, t3 and t4(t4>t3>t2>t1) or simultaneously (t1=t2=t3=t4). The reflected waves ofthe ultrasonic or electromagnetic waves are received by the receiversChA-ChD of the ultrasonic or electromagnetic sensors 6, 8, 9 and 10. Thereceiver ChA is associated with the ultrasonic or electromagnetic sensorsystem 8, the receiver ChB is associated with the ultrasonic orelectromagnetic sensor system 5, the receiver ChD is associated with theultrasonic or electromagnetic sensor system 6, and the receiver ChD isassociated with the ultrasonic or electromagnetic sensor system 9.

FIGS. 10(a) and 10(b) show examples of the reflected ultrasonic wavesUSRW that are received by receivers ChA-ChD. FIG. 10(a) shows an exampleof the reflected wave USRW that is obtained when an adult sits in anormally seated space on the passenger seat 4, while FIG. 10(b) shows anexample of the reflected wave USRW that are obtained when an adult sitsin a slouching state (one of the abnormal seated-states) in thepassenger seat 4.

In the case of a normally seated passenger, as shown in FIGS. 6 and 7,the location of the ultrasonic sensor system 6 is closest to thepassenger A. Therefore, the reflected wave pulse P1 is received earliestafter transmission by the receiver ChD as shown in FIG. 10(a), and thewidth of the reflected wave pulse P1 is larger. Next, the distance fromthe ultrasonic sensor 8 is closer to the passenger A, so a reflectedwave pulse P2 is received earlier by the receiver ChA compared with theremaining reflected wave pulses P3 and P4. Since the reflected wavepauses P3 and P4 take more time than the reflected wave pulses P1 and P2to arrive at the receivers ChC and ChB, the reflected wave pulses P3 andP4 are received as the timings shown in FIG. 10(a). More specifically,since it is believed that the distance from the ultrasonic sensor system6 to the passenger A is slightly shorter than the distance from theultrasonic sensor system 10 to the passenger A, the reflected wave pulseP3 is received slightly earlier by the receiver ChC than the reflectedwave pulse P4 is received by the receiver ChB.

In the case where the passenger A is sitting in a slouching state in thepassenger seat 4, the distance between the ultrasonic sensor system 6and the passenger A is shortest. Therefore, the time from transmissionat time t3 to reception is shortest, and the reflected wave pulse P3 isreceived by the receiver ChC, as shown in FIG. 10(b). Next, thedistances between the ultrasonic sensor system 10 and the passenger Abecomes shorter, so the reflected wave pulse P4 is received earlier bythe receiver ChB than the remaining reflected wave pulses P2 and P1.When the distance from the ultrasonic sensor system 8 to the passenger Ais compared with that from the ultrasonic sensor system 9 to thepassenger A, the distance from the ultrasonic sensor system 8 to thepassenger A becomes shorter, so the reflected wave pulse P2 is receivedby the receiver ChA first and the reflected wave pulse P1 is thusreceived last by the receiver ChD.

The configurations of the reflected wave pulses P1-P4, the times thatthe reflected wave pulses P1-P4 are received, the sizes of the reflectedwave pulses P1-P4 are varied depending upon the configuration andposition of an object such as a passenger situated on the frontpassenger seat 4. FIGS. 10(a) and (b) merely show examples for thepurpose of description and therefore the present invention is notlimited to these examples.

The outputs of the receivers ChA-ChD, as shown in FIG. 9, are input to aband pass filter 60 through a multiplex circuit 59 which is switched insynchronization with a timing signal from the ultrasonic sensor drivecircuit 58. The band pass filter 60 removes a low frequency wavecomponent from the output signal based on each of the reflected waveUSRW and also removes some of the noise. The output signal based on eachof the reflected wave USRW is passed through the band pass filter 60,then is amplified by an amplifier 61. The amplifier 61 also removes thehigh frequency carrier wave component in each of the reflected wavesUSRW and generates an envelope wave signal. This envelope wave signal isinput to an analog/digital converter (ADC) 62 and digitized as measureddata. The measured data is input to a processing circuit 63, which iscontrolled by the timing signal which is in turn output from theultrasonic sensor drive circuit 58.

The processing circuit 63 collects measured data at intervals of 7 ms(or at another time interval with the time interval also being referredto as a time window or time period), and 47 data points are generatedfor each of the ultrasonic sensor systems 6, 8, 9 and 10. For each ofthese reflected waves USRW, the initial reflected wave portion T1 andthe last reflected wave portion T2 are cut off or removed in each timewindow. The reason for this will be described when the trainingprocedure of a neural network is described later, and the description isomitted for now. With this, 32, 31, 37 and 38 data points will besampled by the ultrasonic sensor systems 6, 8, 9 and 10, respectively.The reason why the number of data points differs for each of theultrasonic sensor systems 6, 8, 9 and 10 is that the distance from thepassenger seat 4 to the ultrasonic sensor systems 6, 8, 9 and 10 differfrom one another.

Each of the measured data is input to a normalization circuit 64 andnormalized. The normalized measured data is input to the neural network65 as wave data.

A comprehensive occupant sensing system will now be discussed whichinvolves a variety of different sensors, again this is for illustrationpurposes only and a similar description can be constructed for othervehicles including shipping container and truck trailer monitoring. Manyof these sensors will be discussed in more detail under the appropriatesections below. FIG. 6 shows a passenger seat 70 to which an adjustmentapparatus including a seated-state detecting unit according to thepresent invention may be applied. The seat 70 includes a horizontallysituated bottom seat portion 4 and a vertically oriented back portion72. The seat portion 4 is provided with one or more pressure or weightsensors 7, 76 that determine the weight of the object occupying the seator the pressure applied by the object to the seat. The coupled portionbetween the seated portion 4 and the back portion 72 is provided with areclining angle detecting sensor 57, which detects the tilted angle ofthe back portion 72 relative to the seat portion 4. The seat portion 4is provided with a seat track position-detecting sensor 74. The seattrack position detecting sensor 74 detects the quantity of movement ofthe seat portion 4 which is moved from a back reference position,indicated by the dotted chain line. Optionally embedded within the backportion 72 are a heartbeat sensor 71 and a motion sensor 73. Attached tothe headliner is a capacitance sensor 78. The seat 70 may be the driverseat, the front passenger seat or any other seat in a motor vehicle aswell as other seats in transportation vehicles or seats innon-transportation applications.

Pressure or weight measuring means such as the sensors 7 and 76 areassociated with the seat, e.g., mounted into or below the seat portion 4or on the seat structure, for measuring the pressure or weight appliedonto the seat. The pressure or weight may be zero if no occupying itemis present and the sensors are calibrated to only measure incrementalweight or pressure. Sensors 7 and 76 may represent a plurality ofdifferent sensors which measure the pressure or weight applied onto theseat at different portions thereof or for redundancy purposes, e.g.,such as by means of an airbag or fluid filled bladder 75 in the seatportion 4. Airbag or bladder 75 may contain a single or a plurality ofchambers, each of which may be associated with a sensor (transducer) 76for measuring the pressure in the chamber. Such sensors may be in theform of strain, force or pressure sensors which measure the force orpressure on the seat portion 4 or seat back 72, a part of the seatportion 4 or seat back 72, displacement measuring sensors which measurethe displacement of the seat surface or the entire seat 70 such asthrough the use of strain gages mounted on the seat structural members,such as 7, or other appropriate locations, or systems which convertdisplacement into a pressure wherein one or more pressure sensors can beused as a measure of weight and/or weight distribution. Sensors 7, 76may be of the types disclosed in U.S. Pat. No. 6,242,701 and belowherein. Although pressure or weight here is disclosed and illustratedwith regard to measuring the pressure applied by or weight of an objectoccupying a seat in an automobile or truck, the same principles can beused to measure the pressure applied by and weight of objects occupyingother vehicles including truck trailers and shipping containers. Forexample, a series of fluid filled bladders under a segmented floor couldbe used to measure the weight and weight distribution in a trucktrailer.

Many practical problems have arisen during the development stages ofbladder and strain gage based weight systems. Some of these problemsrelate to bladder sensors and in particular to gas-filled bladdersensors and are effectively dealt with in U.S. Pat. No. 5,918,696, U.S.Pat. No. 5,927,427, U.S. Pat. No. 5,957,491, U.S. Pat. No. 5,979,585,U.S. Pat. No. 5,984,349, U.S. Pat. No. 6,021,863, U.S. Pat. No.6,056,079, U.S. Pat. No. 6,076,853, U.S. Pat. No. 6,260,879 and U.S.Pat. No. 6,286,861. Other problems relate to seatbelt usage and tounanticipated stresses and strains that occur in seat mountingstructures and will be discussed below.

As illustrated in FIG. 9, the output of the pressure or weight sensor(s)7 and 76 is amplified by an amplifier 66 coupled to the pressure orweight sensor(s) 7,76 and the amplified output is input to theanalog/digital converter 67.

A heartbeat sensor 71 is arranged to detect a heartbeat, and themagnitude thereof, of a human occupant of the seat, if such a humanoccupant is present. The output of the heartbeat sensor 71 is input tothe neural network 65. The heartbeat sensor 71 may be of the type asdisclosed in McEwan (U.S. Pat. No. 5,573,012 and U.S. Pat. No.5,766,208). The heartbeat sensor 71 can be positioned at any convenientposition relative to the seat 4 where occupancy is being monitored. Apreferred location is within the vehicle seatback. The heartbeat of astowaway in a cargo container or truck trailer can similarly be measuredbe a sensor on the vehicle floor or other appropriate location thatmeasures vibrations.

The reclining angle detecting sensor 57 and the seat trackposition-detecting sensor 74, which each may comprise a variableresistor, can be connected to constant-current circuits, respectively. Aconstant-current is supplied from the constant-current circuit to thereclining angle detecting sensor 57, and the reclining angle detectingsensor 57 converts a change in the resistance value on the tilt of theback portion 72 to a specific voltage. This output voltage is input toan analog/digital converter 68 as angle data, i.e., representative ofthe angle between the back portion 72 and the seat portion 4. Similarly,a constant current can be supplied from the constant-current circuit tothe seat track position-detecting sensor 74 and the seat track positiondetecting sensor 74 converts a change in the resistance value based onthe track position of the seat portion 4 to a specific voltage. Thisoutput voltage is input to an analog/digital converter 69 as seat trackdata. Thus, the outputs of the reclining angle-detecting sensor 57 andthe seat track position-detecting sensor 74 are input to theanalog/digital converters 68 and 69, respectively. Each digital datavalue from the ADCs 68, 69 is input to the neural network 65. Althoughthe digitized data of the pressure or weight sensor(s) 7, 76 is input tothe neural network 65, the output of the amplifier 66 is also input to acomparison circuit. The comparison circuit, which is incorporated in thegate circuit algorithm, determines whether or not the weight of anobject on the passenger seat 70 is more than a predetermined weight,such as 60 lbs., for example. When the weight is more than 60 lbs., thecomparison circuit outputs a logic 1 to the gate circuit to be describedlater. When the weight of the object is less than 60 lbs., a logic 0 isoutput to the gate circuit. A more detailed description of this andsimilar systems can be found in the above-referenced patents and patentapplications assigned to the current assignee and in the descriptionbelow. The system described above is one example of many systems thatcan be designed using the teachings of at least one of the inventionsdisclosed herein for detecting the occupancy state of the seat of avehicle.

As diagrammed in FIG. 12, the first step is to mount the four sets ofultrasonic sensor systems 11-14, the weight sensors 7,76, the recliningangle detecting sensor 57, and the seat track position detecting sensor74, for example, into a vehicle (step S1). For other vehicle monitoringtasks different sets of sensors could be used. Next, in order to providedata for the neural network 65 to learn the patterns of seated states,data is recorded for patterns of all possible seated or occupancy statesand a list is maintained recording the seated or occupancy states forwhich data was acquired. The data from the sensors/transducers 6, 8, 9,10, 57, 71, 73, 74, 76 and 78 for a particular occupancy of thepassenger seat, for example, is called a vector (step S2). It should bepointed out that the use of the reclining angle detecting sensor 57,seat track position detecting sensor 74, heartbeat sensor 71, capacitivesensor 78 and motion sensor 73 is not essential to the detectingapparatus and method in accordance with the invention. However, each ofthese sensors, in combination with any one or more of the other sensorsenhances the evaluation of the seated-state of the seat or the occupancyof the vehicle.

Next, based on the training data from the reflected waves of theultrasonic sensor systems 6, 8, 9, 10 and the other sensors 7, 71, 73,76, 78 the vector data is collected (step S3). Next, the reflected wavesP1-P4 are modified by removing the initial reflected waves from eachtime window with a short reflection time from an object (range gating)(period T1 in FIG. 11) and the last portion of the reflected waves fromeach time window with a long reflection time from an object (period P2in FIG. 11) (step S4). It is believed that the reflected waves with ashort reflection time from an object is due to cross-talk, that is,waves from the transmitters which leak into each of their associatedreceivers ChA-ChD. It is also believed that the reflected waves with along reflection time are reflected waves from an object far away fromthe passenger seat or from multipath reflections. If these two reflectedwave portions are used as data, they will add noise to the trainingprocess. Therefore, these reflected wave portions are eliminated fromthe data.

Recent advances in ultrasonic transducer design have now permitted theuse of a single transducer acting as both a sender (transmitter) andreceiver. These same advances have substantially reduced the ringing ofthe transducer after the excitation pulse has been caused to die out towhere targets as close as about 2 inches from the transducer can besensed. Thus, the magnitude of the T1 time period has been substantiallyreduced.

As shown in FIG. 13 a, the measured data is normalized by making thepeaks of the reflected wave pulses P1-P4 equal (step S5 of FIG. 12).This eliminates the effects of different reflectivities of differentobjects and people depending on the characteristics of their surfacessuch as their clothing. Data from the weight sensor, seat track positionsensor and seat reclining angle sensor is also frequently normalizedbased typically on fixed normalization parameters. When other sensorsare used for other types of monitoring, similar techniques are used.

The data from the ultrasonic transducers are now also preferably fedthrough a logarithmic compression circuit that substantially reduces themagnitude of reflected signals from high reflectivity targets comparedto those of low reflectivity. Additionally, a time gain circuit is usedto compensate for the difference in sonic strength received by thetransducer based on the distance of the reflecting object from thetransducer.

As various parts of the vehicle interior identification and monitoringsystem described in the above reference patents and patent applicationsare implemented, a variety of transmitting and receiving transducerswill be present in the vehicle passenger compartment. If several ofthese transducers are ultrasonic transmitters and receivers, they can beoperated in a phased array manner, as described elsewhere for theheadrest, to permit precise distance measurements and mapping of thecomponents of the passenger compartment. This is illustrated in FIG. 14which is a perspective view of the interior of the passenger compartmentshowing a variety of transmitters and receivers, 6, 8, 9, 23, 49-51which can be used in a sort of phased array system. In addition,information can be transmitted between the transducers using codedsignals in an ultrasonic network through the vehicle compartmentairspace. If one of these sensors is an optical CCD or CMOS array, thelocation of the driver's eyes can be accurately determined and theresults sent to the seat ultrasonically. Obviously, many otherpossibilities exist for automobile and other vehicle monitoringsituations.

To use ultrasonic transducers in a phase array mode generally requiresthat the transducers have a low Q. Certain new micromachined capacitivetransducers appear to be suitable for such an application. The range ofsuch transducers is at present limited, however.

The speed of sound varies with temperature, humidity, and pressure. Thiscan be compensated for by using the fact that the geometry between thetransducers is known and the speed of sound can therefore be measured.Thus, on vehicle startup and as often as desired thereafter, the speedof sound can be measured by one transducer, such as transducer 18 inFIG. 15, sending a signal which is directly received by anothertransducer 5. Since the distance separating them is known, the speed ofsound can be calculated and the system automatically adjusted to removethe variation due to variations in the speed of sound. Therefore, thesystem operates with same accuracy regardless of the temperature,humidity or atmospheric pressure. It may even be possible to use thistechnique to also automatically compensate for any effects due to windvelocity through an open window. An additional benefit of this system isthat it can be used to determine the vehicle interior temperature foruse by other control systems within the vehicle since the variation inthe velocity of sound is a strong function of temperature and a weakfunction of pressure and humidity.

The problem with the speed of sound measurement described above is thatsome object in the vehicle may block the path from one transducer to theother. This of course could be checked and a correction would not bemade if the signal from one transducer does not reach the othertransducer. The problem, however, is that the path might not becompletely blocked but only slightly blocked. This would cause theultrasonic path length to increase, which would give a false indicationof a temperature change. This can be solved by using more than onetransducer. All of the transducers can broadcast signals to all of theother transducers. The problem here, of course, is which transducer pairshould be believed if they all give different answers. The answer is theone that gives the shortest distance or the greatest calculated speed ofsound. By this method, there are a total of 6 separate paths for fourultrasonic transducers.

An alternative method of determining the temperature is to use thetransducer circuit to measure some parameter of the transducer thatchanges with temperature. For example, the natural frequency ofultrasonic transducers changes in a known manner with temperature andtherefore by measuring the natural frequency of the transducer, thetemperature can be determined. Since this method does not requirecommunication between transducers, it would also work in situationswhere each transducer has a different resonant frequency.

The process, by which all of the distances are carefully measured fromeach transducer to the other transducers, and the algorithm developed todetermine the speed of sound, is a novel part of the teachings of theinstant invention for use with ultrasonic transducers. Prior to this,the speed of sound calculation was based on a single transmission fromone transducer to a known second transducer. This resulted in aninaccurate system design and degraded the accuracy of systems in thefield.

If the electronic control module that is part of the system is locatedin generally the same environment as the transducers, another method ofdetermining the temperature is available. This method utilizes a deviceand whose temperature sensitivity is known and which is located in thesame box as the electronic circuit. In fact, in many cases, an existingcomponent on the printed circuit board can be monitored to give anindication of the temperature. For example, the diodes in a logcomparison circuit have characteristics that their resistance changes ina known manner with temperature. It can be expected that the electronicmodule will generally be at a higher temperature than the surroundingenvironment, however, the temperature difference is a known andpredictable amount. Thus, a reasonably good estimation of thetemperature in the passenger compartment, or other containercompartment, can also be obtained in this manner. Naturally, thermistersor other temperature transducers can be used.

The placement of ultrasonic transducers for the example of ultrasonicoccupant position sensor system of at least one of the inventionsdisclosed herein include the following novel disclosures: (1) theapplication of two sensors to single-axis monitoring of target volumes;(2) the method of locating two sensors spanning a target volume to senseobject positions, that is, transducers are mounted along the sensingaxis beyond the objects to be sensed; (3) the method of orientation ofthe sensor axis for optimal target discrimination parallel to the axisof separation of distinguishing target features; and (4) the method ofdefining the head and shoulders and supporting surfaces as defininghumans for rear facing child seat detection and forward facing humandetection.

A similar set of observations is available for the use ofelectromagnetic, capacitive, electric field or other sensors and forother vehicle monitoring situations. Such rules however must take intoaccount that some of such sensors typically are more accurate inmeasuring lateral and vertical dimensions relative to the sensor thandistances perpendicular to the sensor. This is particularly the case forCMOS and CCD-based transducers.

Considerable work is ongoing to improve the resolution of the ultrasonictransducers. To take advantage of higher resolution transducers, datapoints should be obtained that are closer together in time. This meansthat after the envelope has been extracted from the returned signal, thesampling rate should be increased from approximately 1000 samples persecond to perhaps 2000 samples per second or even higher. By doubling ortripling the amount of data required to be analyzed, the system which ismounted on the vehicle will require greater computational power. Thisresults in a more expensive electronic system. Not all of the data is ofequal importance, however. The position of the occupant in the normalseating position does not need to be known with great accuracy whereas,as that occupant is moving toward the keep out zone boundary duringpre-crash braking, the spatial accuracy requirements become moreimportant. Fortunately, the neural network algorithm generating systemhas the capability of indicating to the system designer the relativevalue of each data point used by the neural network. Thus, as many as,for example, 500 data points per vector may be collected and fed to theneural network during the training stage and, after careful pruning, thefinal number of data points to be used by the vehicle mounted system maybe reduced to 150, for example. This technique of using the neuralnetwork algorithm-generating program to prune the input data is animportant teaching of the present invention.

By this method, the advantages of higher resolution transducers can beoptimally used without increasing the cost of the electronicvehicle-mounted circuits. Also, once the neural network has determinedthe spacing of the data points, this can be fine-tuned, for example, byacquiring more data points at the edge of the keep out zone as comparedto positions well into the safe zone. The initial technique is done bycollecting the full 500 data points, for example, while in the systeminstalled in the vehicle the data digitization spacing can be determinedby hardware or software so that only the required data is acquired.

1.1.2 Thermal Gradients

Thermal gradients can affect the propagation of sound within a vehicleinterior in at least two general ways. These have been termed“long-term” and “short-term” thermal instability. When ultrasound wavestravel through a region of varying air density, the direction the wavestravel can be bent in much the same way that light waves are bent whengoing through the waves of a swimming pool resulting in varyingreflection patterns off of the bottom.

Long-term instability is caused when a stable thermal gradient occurs inthe vehicle as happens, for example, when the sun beats down on thevehicle's roof and the windows are closed. This effect can be reproducedin vehicles in laboratory tests using a heat lamp within the vehicle.The effect has been largely eliminated through training the neuralnetwork with data taken when the gradient is present. Additionally,changes in the electronics hardware including greater signal strengthand a log amplifier, as discussed below, have eliminated the effect.

Short-term instability results when there is a flow of hot or cold airwithin the vehicle, such as caused by operating the heater when thevehicle is cold, or the air conditioner when the vehicle is hot. Benchtests have demonstrated that a combination of greater signal strengthand a logarithmic amplification of the return signal can substantiallyreduce the variability of the reflected ultrasound signal from a targetcaused by short term instability. As with the long-term instability, itis important to train the neural network with this effect present. Whenthe combination of these hardware changes and training is used, theshort-term thermal instability is substantially reduced. If the datafrom five or more consecutive vectors is averaged, the effect becomesinsignificant, see pre and post-processing descriptions below. A vectoris the combined digitized data from, for example in this case, the fourtransducers, which is inputted into the neural network as describedabove.

Different techniques for compensating for thermal gradients are listedin the '979 application incorporated by reference herein, namely insections 1.1.2.1-1.1.2.11.

1.1.3 Audible Noise Elimination

1.1.3.1 Transducer Ringing

Two types of circuits are used in facilitating reduction or eliminationof transducer ringing in accordance with the invention: a linearcircuit, developed on the basis of the Fano theory utilizing theprinciple of physical feasibility to get a “filter-like” circuitstructure (Fano R. M., Theoretical limitations on the broadband matchingof arbitrary impedance, Journal of the Franklin Institute, Vol. 249, pp.57-84 and 139-154 (January-February 1950)), and a non-linear circuit,developed by Automotive Technologies International, Inc. of RochesterHills, Mich. (ATI).

An important purpose of this invention is to obtain an acceptableringing of the transducer at a given drive signal using passiveelectrical components (acceptable meaning within a predeterminedthreshold or range). There is a known general rule that the broader atransducer transfer function is, the shorter the transducer ringing.Various electrical matching circuits with inductors and capacitors werebeing applied to the resonant transducers to widen their transferfunction (May J. E., Waveguide ultrasonic delay lines, PhysicalAcoustics, Edited by W. P. Mason, Vol. 1A. Academic Press, NY-London(1964); White D., A transducer with a locking layer and othertransducers, Physical Acoustics, Edited by W. P. Mason, Vol. 1B.Academic Press, NY-London (1964)). However, the transfer factordecreases if the characteristic is widened arbitrarily. An example ofthis is Massa's commercial ultrasonic transducer of E-152 series, whichbeing tuned with an inductor and a resistor has less sensitivity.Inductive circuits were also applied to medical ultrasonic transducersto widen their frequency response and make their impulse responseshorter. (R. E. McKeighen, Influence of pulse drive shape and tuning onthe broadband response of a transducer, Proc IEEE Ultrasonics Symposium,Vol. 2, pp. 1637-1642, IEEE Cat. #97CH36118, 1997; R. E. McKeighen,Design Guidelines for Medical Ultrasonic Arrays, SPIE InternationalSymposium on Medical Imaging, Feb. 25, 1998, San Diego, Calif.). Theauthor discloses circuits of the specific, low-pass filter structurethat were built on the base of finite element simulations andexperiments carried out with a concrete type of the medical transducerwith lossy backing, that is, with rather low quality factor Q. Theimpulse shortness is observed at the level of about −30 dB that isenough for this type of transducers but not suitable for air-coupledones with high Q. The authors also did not achieve any real ringingreduction of the transducer itself, that is, reduction of electricaloscillations at its electrical terminals (electrodes). Also, as far asthere is no theory underlying the simulations, the study done is onlyapplicable to the concrete type of the transducer investigated.

The known theories of broadband matching of arbitrary impedance,including Fano's, developed on the basis of physical feasibilityapproach (Wai-Kai Chen, Theory and Design of Broadband MatchingNetworks, Pergamon Press, Oxford N.Y. Toronto Sydney Paris Frankfurt,1976; Matthaei G. L., Young L., Jones E. M. T., Microwave filters,impedance matching networks, and coupling structures, Vol. 1,McGraw-Hill Book Company, NY 1964)) give techniques of how to integratea lumped model of matched impedance into a filter-like structure, andthen to build an optimal matching circuit that provides, for example, amaximum transfer factor at a given bandwidth.

Similar approaches are disclosed in (G. A. Hjellen, J. Andersen, R. A.Sigelmann, “Computer-aided design of ultrasonic transducer broadbandmatching networks”, IEEE Trans on Sonics and Ultrasonics, Vol. SU-21,No. 4, PP. 302-305, October, 1974; C. H. Chou, J. E. Bowers, A. R.Selfridge, B. T. Khuri-Yakub, and G. S. Kino. The Design of Broadbandand Efficient Acoustic Wave Transducers, Preprint G. L: Report No. 3191November 1980. Presented at 1980 Ultrasonics Symposium, November 4-7,1980, Boston, Mass.). In the first case, the authors built athree-element lumped R-L-C model of the high frequency (5.5 MHz)transducer, integrated it in the pass-band filter-like structure withseries inductive and capacitive elements, and then applied a parametricsynthesis procedure to those elements to get a wide Butterworth-likecharacteristic of the electrical power absorbed by the transducer. Theydid not analyze and reduce ringing of the transducer. In the secondcase, the authors also applied parametric synthesis to high frequency (3MHz and 35 MHz) lossy backing transducers operating into water, andbuild reactive matching circuits with inductors and capacitors to geteither a desirable frequency response or a compact impulse response ofthe transducer. They shortened the impulse response of the 35 MHztransducer from 15 full cycles to 3 full cycles. However, they do notdisclose ringing reduction of the transducer at its electrical terminalsor the drive signal shape at which this compactness of the impulseresponse was achieved.

One of optimal matching techniques, namely Fano's, being applied topiezo-transducers with low quality factor Q (Yurchenko A. V. Broadbandmatching of piezo-transducers of acousto-optic devices. Izvestiya VUZ.,Radioelektronika, Vol. 23, No. 3, pp. 98-101, (1980); Tsurochka B. N.,Yurchenko A. V., An electroacoustic device, USSR Author certificate No.1753586 Int. Cl.⁵H03 07/38 (1992)) enabled optimal matching of thetransducers within an arbitrary frequency band using parallel/seriesinductors and capacitors. It is also disclosed (T. L. Rhyne, Method fordesigning ultrasonic transducers using constraints on feasibility andtransitional Butterworth-Thompson spectrum, U.S. Pat. No. 5,706,564) howto design an ultrasonic half-wavelength transducer with a desirableshape of the bandpass characteristic.

None of disclosed techniques suggests what a characteristic shape orbandwidth is desirable to minimize ringing. This is a multi-parametertask that could be solved in alternative ways depending on what factoris most important for concrete applications. Therefore, to get reducedringing, one can consider the Murata transducer as a two-port transducerwith known input impedance, apply the Fano method to get a bandwidthwith acceptable transfer factor and/or an acceptable inductor value, andthen smooth the phase characteristic to get acceptable transducerringing at a given input electrical signal. Such a procedure has beenused in this invention to synthesize a linear electrical circuit forringing reduction. The circuit synthesized has been simulated and thenexamined experimentally. All of the above references are incorporatedherein by reference.

The non-linear circuit has been simulated and the influence of itsparameters on ringing reduction was investigated. In both simulations, aconditional Spice model of the Murata transducer MA40S4R/S was built onthe basis of the heuristic approach. The measured transducer impedancewas used as initial data.

The operation of the transducer in dual-function (i.e.,transmitter-receiver) mode is fundamentally different from itstransmitter mode. To see the difference, a transducer operating indual-function mode will be considered in greater detail. In view of theinterest in detecting small signals reflected back from a target, apossibility to shorten the ringing zone (dead zone as it is frequentlycalled) will depend on what ringing is present at the electrical inputto the transducer. It does not matter much what ringing will be at thetransducer acoustic output. The dead zone length will be determinedsubstantially exclusively by the relation of the received signal levelto a ringing floor at the transducer electrical side. Although transientprocesses at the transducer electrical input and its acoustic output areconnected due to electromechanical coupling, they are not identicalbecause of the non-symmetry of the electromechanical two-port anddifferent boundary conditions at its electrical and acoustic sides.Thus, the transient electrical process at the input of the transducershould be considered and its level compared with a level of delayedburst detected at the same points of electrical circuit. Such ananalysis has been performed using the MicroSim® DesignLab 8.0(evaluation version) Spice modeling software. Its results are presentedbelow.

To build a Spice model of the Murata transducer means to find thestructure of an electrical circuit approximating the transfer functionof the electromechanical two-port device and find parameters of itscomponents. If the transducer operates in dual-function mode, it isnecessary to realize circuits for both transmitter and receiver modes.In this analysis, a simplified heuristic procedure is used. The idea isto build the simplest equivalent circuit of the transducer and adapt itto both modes without taking into account real values of the transferfactors, then to build a Spice model of air medium using a delay linefrom the software library. It was supposed that decay in the mediumSpice model would emulate both the transducer transfer factor and lossin air. It was known from experiments that at exciting burst of 20 Vpp,the Murata transducers had received signals of about 20 mV. Therefore, avalue of the medium decay was selected in order to see a delayed signalat the level of about −60 dB related to the electrical input (16 Vpp).In this manner, it was possible to observe and analyze distortions ofthe received signals caused by both the transducer and a circuit underconsideration without having an exact Spice model based on theequations.

The common view of the Spice model built is presented in FIG. 37. Themodel has a block structure. The internal structures of the blocks aredetermined by its functions. The “Medium” and “SourceTC/SourceTC_r”blocks (shown in FIGS. 38 and 39, respectively) have identicalstructures in all simulations. Blocks “Transducer” and “Transducer_r”have identical components and structure but the simulating electricalsignals are applied to them in different ways depending on thetransmitter/receiver modes. The “Circuit”/“Circuits_r” blocks emulatethe circuit under consideration, linear or non-linear. They areidentical in the same simulation.

The “Medium” Spice model (FIG. 38) has been realized using twovoltage-controlled sources E1 and E2, and delay line T1.

Since the MicroSim® software does not have in its library driver TC4426which is the signal source in the ATI electronics, the“SourceTC/SourceTC_r” Spice model (FIG. 39) has been determinedartificially on the basis of documentation on the driver. “SourceTC/ . .. ” that provides “Repeat value”=n cycles of a symmetrical rectangularsignal of 16 Vpp across its terminals “Output1,Output2”. The cycleduration has been established equal to 25.8 microsec. This correspondsto frequency f, of dynamic resonance of the transducer that happened tobe equal to 38.78 kHz. According to documentation, the driver outputresistance is 11+11 Ohm at V_(DD)=8 V.

The conventional equivalent circuit (Berlincourt D., Kerran D., JaffeH., Piezoelectric and piezomagnetic materials, Physical Acoustics,Edited by W. P. Mason, v. 1. Academic Press, NY-London (1964)) of thetransducer is just the equivalent circuit of a piezoelectric resonator(FIG. 40). It has been built on the basis of electrical measurements.Complex input admittance y(f) of ten units of the Murata MA40SR/Stransducers were measured using a Network Analyzer HP3577A. Averagedresults of measurements are presented in FIGS. 6 and 7 of the parent'159 application. The obtained data was interpolated with cubic splinesusing Mathcad® 2000 software and then used to calculate the equivalentcircuit parameters:R ₀ =Re(y(f _(s)))⁻¹ , L ₁ =QR ₀/2πf _(s) , C ₁=1/(2πf _(s))² L ₁ , C ₀=Im(y(f _(s)))/2πf _(s).

The dynamic resonance frequency has been found as a frequency thatcorresponded to maximum of interpolated numeric function Re(y(f)). TheQuality factor Q was calculated as Q=f_(s)/Δf, where Δf was determinedat the half level of curve Re(y(f)).

The parameters found were R₀=362 Ohm, L₁=58.6 mH, C₁=287 pF, C₀=2.55 nF,Q=39. These values were used in the transducer Spice model (FIG. 41). Itis exactly its equivalent circuit but with two ports (AcoucticOut1,AcousticOut2) and (AcoucticIn1, AcousticIn2) which allows the transducertransmitter or receiver mode to be emulated. The transmitter mode isrealized when a short is installed at the port (AcoucticIn1,AcousticIn2) (see FIG. 37). In this case, the “Transducer” two-portemulates the signal transfer from “Circuit” to “Medium”. Its first port,(AcoucticOut1, AcousticOut2), emulates acoustic output. To analyze thetransducer transfer and transient functions, the total loss resistanceis considered instead of true radiation resistance. A small value of theelectro-acoustic transfer factor is taken into account in the “Medium”decay.

When the receiver mode is realized, emf, emulating input acousticsignal, is applied to port (AcoucticIn1, AcousticIn2). Port(AcoucticOut1, AcousticOut2) is left open. In this case, the“Transducer_r” two-port emulates the signal transfer from “Medium” to“Circuit”.

The “Circuit/Circuit_r” blocks are identical in the transmitter orreceiver modes. Their terminals (Ring1, Ring2) and (Test1, Test2) usedto test differential signals under consideration are also identical.They are given different names only to distinguish the “Circuit” modes,transmitter or receiver. There is one more port in the total Spice modelto test a shape (but not a level) of the acoustic signal radiated. It is(AcoucticOut1, AcousticOut2) in the “Transducer”. Voltage across thosethree ports is just the signals that had been analyzed while circuitsunder consideration were being investigated.

-   -   The results of the simulation were as follows.    -   The non-linear circuit will be discussed initially.

FIG. 42 shows the non-linear circuit presented for an analysis but withone exception: the Murata transducer MA40S5 was replaced with transducerMA40S4R/S. That was done because transducers MA40S4R/S were available tomake measurements. It is believed that the results obtained withtransducers MA40S4R/S should not be very different from the resultsobtained with transducers MA40S5.

The Spice model of the non-linear circuit is presented in FIG. 43. It isexactly the part between driver TC4427 and resistors R6, R7 of thecircuit in FIG. 42. The branch “Shunt” emulates total impedance ofresistors R6, R7 and input impedance of circuit “To Signal Conditioning”which is unknown. For a particular reason, which will be explainedbelow, the shunt is supposed to be equal to 3 k.

In FIG. 10 of the parent '159 application, signals observed undertransient analysis are presented. The “SourceTC” output is establishedto be 8 cycles, i.e., of 0.2 ms duration. The “conditional” acousticoutput of the transducer displays only the output burst shape but notits level. The remaining curve shows the electrical signal at testpoints. Just this signal is one of interest. Its “tail” forms a ringfloor that interferes with received signals and increases a dead zone.The “received” signal is not shown in FIG. 10 of the parent '159application because of the low sensitivity of the simulation display(used scale from −10V to 10V). The conditions under which the analysishas been done are shown in FIG. 10 of the parent '159 application.“Delay” is the delay line parameter that allows simulation of differentdistances to a target and the analysis of the interference of theringing and the received signals. That was being done at the scale of−10 mV, 10 mV, that is, at the level of about −60 dB related to theelectrical input. Such diagrams are presented in FIGS. 11 and 12 of theparent '159 application. Here, the interfere signal (ringing), thereceived signal and a conditional radiated acoustic burst signal areshown. The latter signal is rendered only for information. Anyestimation using it is impossible because it only emulates acousticburst that is not present at electrical side of the transducer.

Displays rendered in FIGS. 11 and 12 of the parent '159 application showthe difference observed when different diodes are used in the circuit.When signal diodes (1N914) with relatively small forward current (100mA) and small recovery time (4 ns) are used, the signal shape is less“pure” than in case of rectifier diodes (1N4002) but ringing is shorter.

The first step in the analysis was to investigate the influence of the“To Signal Conditioning” circuit input resistance that was emulated with“Shunt”. Results when it is of about 100 k are presented. One can seethe distortion of the received signals. Under certain conditions, thereceived signal can only be treated as several signals (FIG. 11 of theparent '159 application). From FIGS. 13, 14 and 15 of the parent '159application, one can see what happens to signals when the resistance ofthe shunt decreases. Three main effects are observed: the signal shapebecomes more pure, the ringing decreases, and the signal level alsodecreases. If the main criterion is to reduce the ringing duration, thebest result is observed when the shunt resistance is about 3 k. In thiscase, the signal level does not decrease significantly and thus theshunt resistance of 3 k was chosen in all further simulations. Thiscorresponds to input resistance of “To Signal conditioning” circuit ofabout 1 k.

FIG. 16 of the parent '159 application shows the shape of the signalreceived for the same conditions as in FIG. 15 of the parent '159application except that the delay in the medium is 0.7 ms. Similarly,FIG. 17 of the parent '159 application shows the shape of the signalreceived for the same conditions as in FIG. 15 of the parent '159application except that the delay in the medium is 0.6 ms and FIG. 18 ofthe parent '159 application shows the shape of the signal received forthe same conditions as in FIG. 15 of the parent '159 application exceptthat the delay in the medium is 0.5 ms.

In this case, the signal shape and ringing duration are so good thatdelay time in simulation can be decreased to 0.6 ms when the receivedsignal maximum is observed at 0.8 ms (see Probe Cursor in FIG. 17 of theparent '159 application). The received signal can be even easilydetected at 0.7 ms when the delay time is established 0.5 ms (ProbeCursor, FIG. 18 of the parent '159 application). Thus, the circuit underconsideration provides satisfactory results.

An analysis of the manner in which the circuit parameter variationsaffect its characteristics is as follows. First, the ringing durationwill be considered.

To compare different versions, we will define ringing duration as a timeat which the ringing floor is approximately 10 times less than a maximumlevel of the signal received. In FIGS. 19-24 of the parent '159application, the ringing floor is represented by cursor A2 and themaximum level of the signal received is represented by A1.

The main electrical element used to suppress ringing in the circuitunder consideration is inductance L1=6 mH. So, variations of its branchwill mainly be analyzed. FIG. 19 of the parent '159 application displaysthe result when the circuit has original parameters. (Note there is somedifference with FIG. 15 of the parent '159 application in which thecircuit has identical parameters. It is due to more exact analysisperformed here: the time step in the transient analysis was decreasedfrom 1 μs to 0.2 μs). FIGS. 20 and 21 of the parent '159 applicationshow the effect of changing R5 by 50%. An increase of R5 is equivalentto the quality factor decrease of the inductance branch, and vice versa.One can see that the greater quality factor, the less the ringingduration is (FIG. 21 of the parent '159 application), but generally, itsinfluence is not significant (tens microseconds). It is another matterwhen inductance itself is changed (FIGS. 22-24 of the parent '159application). Variations of 10% inductance related to its original valueof 6 mH result in changes of ringing duration by hundreds ofmicroseconds. The remarkable fact is that the best result occurs wheninductance is equal to 6.6 mH, i.e., it is just tuned with thetransducer capacitance C₀ at the transducer dynamical resonancefrequency f_(s) equal to 38.8 kHz for model simulated. Further increaseof the inductance up to 7.2 mH (by another 10%) deteriorates the result(FIG. 24 of the parent '159 application).

From the simulation and analysis performed one can conclude thefollowing:

-   -   the original non-linear circuit provides necessary ringing        suppression of the Murata transducers MA40S4R/S and pure        received signals if the inductance branch (the transducer input)        is shunted with resistance of several kOhm. The ringing        suppression is of such value that received signals could be        easily detected at time of 0.7 ms. The payment for that is        reduction of the signal received;    -   without the shunt, significant distortions of the received        signal are observed which can be treated as additional        reflections from a target; and    -   the original circuit characteristics could be improved with more        exact tuning of the inductance value L1 but expected improvement        is not significant. Thus, the circuit parameters are close to        optimal.        -   A linear circuit optimized on the basis of Fano's theory            will now be discussed.

The method developed for broadband matching of piezoelectric transducersin Yurchenko A. V., Broadband matching of piezo-transducers ofacousto-optic devices, Izvestiya VUZ., Radioelektronika, vol. 23, No. 3,pp. 98-101, (1980), was used to build a circuit for ringing suppression.Preliminary simulation and experiment showed that the simplest matchingcircuit (FIG. 44) with optimal by Fano Chebyshev transfer functiontr _(—) f=20 log(U _(out) /E)of the second order could provide a necessary bandwidth if theinductance value were of about 2 mH. The circuit was synthesized to getparallel inductance of 2.2 mH because the industry produces suchinductors of small sizes and rather high quality factor (Q>30). Then thecircuit obtained was modified to get a smooth phase transfer functiondue to fitting the resistive impedance of the generator R_(g). Thatresults in a reduced ringing duration at the “conditional acousticoutput”, resistance R_(g). Hence, ringing at the transducer input shouldbe also reduced.

FIG. 44 shows an equivalent circuit of the transducer with a matchingcircuit.

With respect to FIGS. 26A, 26B, 26C and 26D of the parent '159application, the following data is relevant:

Circuit:

δ=0.131

R_(g)=1400 Ω

L₂=2.203 mH

C₂=7.645 nF

C₀=2.553 nF

C_(add)=5.092 nF

Δf_(Fano)=7.51 kHz

L₁=58.586 mH

C₁=287 pF

R₀=362 Ω

Q=39.428

Signal:

f_(s)=38.78 kHz

f₀=38.78 kHz

n=8

Data:

ReNmb=21

ImNmb=22

Averaged data Numbers 21@22

Results:

f: 34 kHz, 34.1 kHz . . . 44 kHz

A special Mathcad® 2000 code to synthesize circuits with given ringingduration was developed and applied to the circuit design. Results ofcalculations are presented in FIGS. 26A, 26B, 26C and 26D of the parent'159 application. One can see that ringing in the total circuit is small(<0.5 ms) but losses are large (˜13 dB) because of large resistanceR_(g). The large value of losses creates an impression that it isineffective to apply the circuit. But this is not so. In actuality, dueto the widening of the bandwidth, the input burst has time “to swing”the transducer, and the output reaches its maximum value. It is clearlyseen in FIG. 26C of the parent '159 application (see output burst in thelow left corner). Another point is that in the receiving mode the signalreceived is detected on the large resistance R_(g), that is, thetransducer sensitivity will not be reduced significantly. Thus, one canexpect good results applying the circuit synthesized. This circuit, aswell as the non-linear one analyzed above, has been simulated with theMicroSim® DesignLab software using the same total Spice model but withanother “Circuit”.

The linear “Circuit” Spice model used in simulation is shown in FIG. 45.It has the simplest structure of a pass-band filter. Resistors R_(ga)and R_(gb) emulate the necessary value of the source output resistance.Inductor L2=2.2 mH of the Coilcraft® type DS1608-225 has the qualityfactor Q=31 given in the documentation. Losses of the capacitor C_(add)have been taken arbitrarily. In simulation they are chosen large enoughto have “a reserve” in practice.

The simulation results are presented in FIGS. 28-33 of the parent '159application. FIG. 28 of the parent '159 application shows that themaximum voltage across test points (Test1, Test2), i.e., at electricalside of the transducer, is less than in case of the non-linear circuit(FIG. 10 of the parent '159 application). It is caused by losses on theresistor R_(g) and smoothing of the transient response of the totalcircuit. From FIGS. 29-32 of the parent '159 application, it can be seenthat the simulation results obtained with the circuit underconsideration are similar to ones obtained with the non-linear circuitabove but worse. Their improvement can be made in different ways. Theclassical one is to get the higher order transfer function. It requiresanother couple of an inductor-capacitor. Another way is to add somenon-linear components.

The result obtained in this way is presented in FIG. 33 of the parent'159 application.

In addition, simulations with the Spice model provide results worse thanone could expect from calculations made with Mathcad® 2000. In thosecalculations, “visible” ringing at “acoustic output” is less than 0.5 ms(t/T=20 in FIGS. 26A-26D of the parent '159 application). In the circuitSpice model, it is evidently longer (FIGS. 28-32 of the parent '159application). Apparently, it is connected with losses that were nottaken into account in the mathematical model.

From the simulation and analysis performed one can conclude thefollowing:

-   -   the simplest second order linear circuit based on the Fano        theory provides necessary ringing suppression of the Murata        transducers MA40S4R/S and pure received signals but its        characteristics are worse than those of the optimized non-linear        circuit considered above. The ringing suppression is of such        value that received signals could be easily detected at time of        0.9 ms;    -   the circuit characteristics could be improved with added        non-linear components; and    -   to improve characteristics significantly, a more complicated        circuit should be designed with higher order transfer function.        It requires the addition of one or more capacitors and one or        more inductors.        -   Experimental examination of the linear circuit is as            follows.

The linear circuit discussed above was investigated experimentally. Formeasurement convenience, it was realized in a non-differential version(shown in FIG. 46 and designated the “Circuit”). Its complex inputimpedance, relative sound pressure while input was applied to points Aor B, and ringing duration have been measured for three transducers(##7, 13, 14) arbitrarily selected from the sample of 10 units whoseaveraged characteristics were used in calculations (see above). Inputimpedance was measured by means of a Network Analyzer HP3577A. Soundpressure was measured at the distance of 30 cm with the ¼″ microphone.Absolute measurements were not made, rather, only comparativecharacteristics at different input points A/B were obtained. Ringingduration and the signal reflected back from a target (2″ disk) locatedat the distance about 10 cm were measured with the measurement setupshown in FIG. 46 at tone burst input of 20 Vpp and 0.2 ms duration. Noadditional diodes or resistors at the gated amplifier output and atoscilloscope input were used. Obtained frequency characteristics arepresented in FIGS. 35 and 36 of the parent '159 application. A typicalview on the oscilloscope display while the ringing was measured ispresented in FIG. 37 of the parent '159 application. Measured signalsparameters are collected in Table 1. TABLE 1 Operating Signal, reflectedDistance Transducer frequency, from the target, Delay time, to the # kHzmVpp ms target, cm 7 38.67 60 0.8 ≦10 13 39.57 80 0.8 ≦10 14 39.20 700.8 ≦10

Both input impedance z(f) and sound pressure p(f) characteristics show abroadband bandwidth of the device. The sound pressure plot has a linearscale, it illustrates that the bandwidth widening and simultaneousreduction of acoustic output: sound pressure has been reduced by aboutthree times, that is, by about 10 dB. Nevertheless, as one can see inFIG. 37 of the parent '159 application, signals reflected back from atarget, were not very small: on the order of about 70 mVpp. Hence, theycan be easily detected when the target was located at the distance ofabout 10 cm and even less, that is, the observed ringing duration didnot exceed 0.6 ms. Data presented in Table 1 confirm the observations.

Thus, the circuit under consideration gives good results demonstratingthat even the simplest linear electrical circuit of the second order cansuppress ringing of the Murata dual-function transducers to a requiredlevel and provide reliable detection of signals reflected from targetslocated nearer 10 cm. From the experiments, another important conclusionfollows that the manufactures tolerances do not prevent obtainingacceptable ringing with the same electrical circuit for differentsamples of the Murata transducers.

In sum, as discussed above, non-linear and linear electrical circuitsfor ringing suppression of the Murata transducers were investigated. Thelinear circuit has been designed on the basis of the Fano theory of thebroadband matching of arbitrary impedance. The approach has beendeveloped to improve its transient function and get a necessary ringingreduction. Input impedance of the dual-function transducers MA40S4R/Shas been measured and used to build the transducer model. The Spicemodels of the circuits and transducers were built and simulated usingthe MicroSim® LabDesign software.

From simulation results, one can conclude the following:

-   -   both linear and non-linear circuits provide a transducer ringing        suppression to a required level. The ringing suppression is of        such value that received signals could be easily detected at        time of 0.7-0.9 ms (non-linear and linear ones correspondingly);        and    -   the non-linear circuit gives better results than the simplest        linear one of the second order.

Characteristics of the linear circuit can be improved with additionalnon-linear components. The linear circuit was built and examinedexperimentally. From experimental results one can conclude that:

-   -   even the simplest linear electrical circuit of the second order        gives good results. It can suppress ringing of the Murata        dual-function transducers to a required level and provide        reliable detection of signals reflected from targets located        nearer 10 cm. In this case, the received signal level is about        70 mVpp;    -   the manufactures tolerances do not prevent from getting        acceptable ringing with the same electrical circuit for        different samples of the Murata transducers.

FIG. 47 is a circuit diagram of another embodiment of the inventionwherein a switching device such as a gate is provided to enableswitching between a plurality of circuits formed by electricalcomponents. In this circuit, a gate signal turns on transistors Q5 andQ8 during the ring down time. Inductor L1 and Resistor R38 are switchedacross the transducer during the ring down time. Inductor L1 andResistor R38 are disconnected from the transducer during echo time sothat the signal will not be attenuated. The gate is controlled or timedby a microprocessor, not shown.

Generally, a circuit with a switch such as shown in FIG. 47 is simplerand less expensive than a circuit designed using Fano's theory. Asdiscussed above, a circuit using Fano's theory is one in which the bestmatching components are found for both the transmission of an ultrasonicpulse and reception of an ultrasonic pulse. The objective is toeliminate the ringing without losing sensitivity.

In the circuit shown in FIG. 47, as soon as the transmission of theultrasonic pulse is finished, the switched is activated to alter thecircuit during the reception time. Once the reception time is complete,or when the next transmission is to be sent, the switch is againactivated to alter the circuit back to the transmission circuit. Thus,two circuits are formed from the electronic components, one operativeduring transmission and the other during reception. These circuits maybe formed from two sets of components without duplication, one set ofcomponents wherein some are removed from one or each of the circuits toprovide the different circuits, or one set of components wherein thecharacteristics of the components are variable, e.g., a variableresistor.

In light of the circuit shown in FIG. 47, a method for reducing ringingof dual-function ultrasonic transducers would comprise the steps ofproviding a plurality of electrical components at least one of which iscapable of providing inductance, coupling a switching device with thecomponents to enable the construction of at least a first circuit and asecond circuit depending on the status of the switching device,selectively coupling the components to the transducer such that theinductance-providing component is in series and/or in parallel with thetransducer, and controlling the switching device in conjunction with theoperation of the transducer such that the first circuit is coupled tothe transducer during a transmission mode of the transducer and thesecond circuit is coupled to the transducer during the reception mode ofthe transducer. In this manner, the objective of obtaining a decreaseddead zone of the transducer can be realized.

In other words, one electrical reactive circuit or network may beswitched on during the setting time and then switched out. If thenetwork is left switched in after the setting time, then the gain in thereceive mode is greatly reduced. Thus, one advantage of switching thetransmission network out during the reception mode is that reductions ingain are substantially avoided.

In sum, the present invention for ringing reduction in ultrasonictransducers relates to the design and construction of electricalcircuits to suppress ringing of ultrasonic air-coupled resonanttransducers. It is important to appreciate that a significant differencebetween the invention and prior art discussed above is that in theinvention, electrical oscillations at the transducer terminals areanalyzed whereas in prior art discussed above, emitted ultrasound pulsesare investigated.

1.1.3.2. Clicking Reduction

In addition to ringing, another undesirable feature of ultrasonictransducers when used in the interior of vehicles is an audible clickingnoise. Although there is some disagreement as to the exact cause of thephenomenon, at least one theory relates it to the nonlinearityassociated with the adiabatic expansion and compression in air caused bythe ultrasonic wave. Many attempts have been made to solve the problemincluding varying the envelope of the ultrasonic pulse. This has hadlittle effect if the pulse energy level is kept constant. That is, theclicking remains essentially the same for the same total ultrasonicenergy providing the length of the pulse remains the same regardless ofthe shape of the pulse envelope. This is in contrast to that reported inU.S. Pat. No. 6,243,323. Lengthening the pulse and reducing the peakamplitude does reduce the clicking but at the expense of reducedresolution of the ultrasonic image and thus accuracy of classificationand location algorithms. If the distance to a single reflecting surfaceis desired, then this technique can be used, but usually there are manysurfaces that reflect the ultrasonic waves and in order to separate onesurface from another, it is desirable to have the pulse as short aspossible, that is, to have as few cycles as possible.

It has been discovered that it is possible to filter the ultrasoundpulse such that lower frequencies in the audio range are reduced morethan the higher ultrasonic frequencies through the use of a mechanicalfilter. One such arrangement including a mechanical filter isillustrated in FIG. 48 which is a cross-sectional view of a MuRata typeultrasonic transducer 100 placed within a horn 120 having a conicalsection and a cylindrical section. The transducer 100 includes a case101, a cone 102, a metal plate 103, a piezoelectric ceramic member 104,a base 112, a conductive metal plate 113, wires 114 and 115 and leadterminals 116. A mechanical filter 117 is arranged above the transducer100 and also contained by the horn 120. Accordingly, the cone 102 andfilter 110 are arranged inside of a common housing, i.e., the horn 120,and such that the cone 102 and filter 110 are peripherally surrounded bythe horn 120. Also, the cone 102 is arranged in the case 101 whichseparates the filter 110 from the cone 102 and in a housing, e.g., thehorn 120, which has an opening at one end through which the ultrasonicsound waves pass with the filter 110 being interposed between the cone102 and the opening.

In this embodiment of the invention, the filter 117 may comprise of opencell foam made, for example, from polyurethane or silicone, andtypically has a density of about 1.5 to 7 pounds per cubic foot.Narrower ranges include from about 1.5 to about 3 pounds per cubic footand from about 4 to about 7 pounds per cubic foot. The cell size forfoam having a density of 1.5 to 3 pounds per cubic foot varies fromabout 25 to about 250 μm. Generally, no foam has entirely one type ofcell structure, but rather, open or closed cell structure implies thatthe number of cells in the foam is predominantly open or closed,respectively. The material of the foam can be various types of plasticor rubber.

This design resulted in a reduction of the audible clicking frequenciesby about 6 db and of the 40 kHz ultrasound by about 3 db. In order tomaintain the same output, the transducer drive voltage had to beincreased. The final result was to reduce the clicking below thethreshold of human hearing while maintaining the ultrasound pulse toabout 9 cycles, which was sufficient to separate two targets that wereseparated by 2 inches.

The foam used also has the advantage of protecting the transducer 100from contamination which can occur when the device is used in vehiclessuch as automobiles, cargo containers, boats, airplanes, trucks andtruck trailers and vehicle trunks. Although foam produced the desiredresult, it is expected that there are many other constructions andgeometries of filters that would also accomplish similar results and mayeven be more efficient. Various baffle or tuned chamber designs, forexample, show promise of selectively trapping longer waves and allowingthe shorter waves to pass more freely. Similarly, a transducer cavitycan be designed to cause certain waves to cancel while permitting othersto pass. Since there are undoubtedly many solutions that will now becomeevident to those skilled in the art, this invention is not limited tothe use of a plastic or rubber foam material as a filter. Any mechanicalmeans of selectively reducing waves of a certain frequency rangerelative to another frequency range is contemplated.

1.2 Optics

In FIG. 4, the ultrasonic transducers of the previous designs arereplaced by laser transducers 8 and 9 which are connected to amicroprocessor 20. In all other manners, the system operates the same.The design of the electronic circuits for this laser system is describedin some detail in U.S. Pat. No. 5,653,462 and in particular FIG. 8thereof and the corresponding description. In this case, a patternrecognition system such as a neural network system is employed and usesthe demodulated signals from the laser transducers 8 and 9.

A more complicated and sophisticated system is shown conceptually inFIG. 5 where transmitter/receiver assembly 52 is illustrated. In thiscase, as described briefly above, an infrared transmitter and a pair ofoptical receivers are used to capture the reflection of the passenger.When this system is used to monitor the driver as shown in FIG. 5, withappropriate circuitry and a microprocessor, the behavior of the drivercan be monitored. Using this system, not only can the position andvelocity of the driver be determined and used in conjunction with anairbag system, but it is also possible to determine whether the driveris falling asleep or exhibiting other potentially dangerous behavior bycomparing portions of his/her image over time. In this case, the speedof the vehicle can be reduced or the vehicle even stopped if this actionis considered appropriate. This implementation has the highestprobability of an unimpeded view of the driver since he/she must have aclear view through the windshield in order to operate the motor vehicle.

The output of microprocessor 20 of the monitoring system is shownconnected schematically to a general interface 36 which can be thevehicle ignition enabling system; the entertainment system; the seat,mirror, suspension or other adjustment systems; telematics or any otherappropriate vehicle system.

FIG. 8A illustrates a typical wave pattern of transmitted infrared wavesfrom transmitter/receiver assembly 49, which is mounted on the side ofthe vehicle passenger compartment above the front, driver's side door.Transmitter/receiver assembly 51, shown overlaid ontotransmitter/receiver 49, is actually mounted in the center headliner ofthe passenger compartment (and thus between the driver's seat and thefront passenger seat), near the dome light, and is aimed toward thedriver. Typically, there will be a symmetrical installation for thepassenger side of the vehicle. That is, a transmitter/receiver assemblywould be arranged above the front, passenger side door and anothertransmitter/receiver assembly would be arranged in the center headliner,near the dome light, and aimed toward the front, passenger side door.Additional transducers can be mounted in similar places for monitoringboth rear seat positions, another can be used for monitoring the trunkor any other interior volumes. As with the ultrasonic installations,most of the examples below are for automobile applications since theseare generally the most complicated. Nevertheless, at least one of theinventions disclosed herein is not limited to automobile vehicles andsimilar but generally simpler designs apply to other vehicles such asshipping containers, railroad cars and truck trailers.

In a preferred embodiment, each transmitter/receiver assembly 49, 51comprises an optical transducer, which may be a camera and an LED, thatwill frequently be used in conjunction with other opticaltransmitter/receiver assemblies such as shown at 50, 52 and 54, whichact in a similar manner. In some cases, especially when a low costsystem is used primarily to categorize the seat occupancy, a single ordual camera installation is used. In many cases, the source ofillumination is not co-located with the camera. For example, in onepreferred implementation, two cameras such as 49 and 51 are used with asingle illumination source located at 49.

These optical transmitter/receiver assemblies frequently comprise anoptical transmitter, which may be an infrared LED (or possibly a nearinfrared (NIR) LED), a laser with a diverging lens or a scanning laserassembly, and a receiver such as a CCD or CMOS array and particularly anactive pixel CMOS camera or array or a HDRL or HDRC camera or array asdiscussed below. The transducer assemblies map the location of theoccupant(s), objects and features thereof, in a two or three-dimensionalimage as will now be described in more detail.

Optical transducers using CCD arrays are now becoming price competitiveand, as mentioned above, will soon be the technology of choice forinterior vehicle monitoring. A single CCD array of 160 by 160 pixels,for example, coupled with the appropriate trained pattern recognitionsoftware, can be used to form an image of the head of an occupant andaccurately locate the head, eyes, ears etc. for some of the purposes ofat least one of the inventions disclosed herein.

The location or position of the occupant can be determined in variousways as noted and listed above and below as well. Generally, any type ofoccupant sensor can be used. Some particular occupant sensors which canbe used in the systems and methods in accordance with the invention.Specifically, a camera or other device for obtaining images of apassenger compartment of the vehicle occupied by the occupant andanalyzing the images can be mounted at the locations of the transmitterand/or receiver assemblies 49, 50, 51, and 54 in FIG. 8C. The camera orother device may be constructed to obtain three-dimensional imagesand/or focus the images on one or more optical arrays such as CCDs.Further, a mechanism for moving a beam of radiation through a passengercompartment of the vehicle occupied by the occupant, i.e., a scanningsystem, can be used. When using ultrasonic or electromagnetic waves, thetime of flight between the transmission and reception of the waves canbe used to determine the position of the occupant. The occupant sensorcan also be arranged to receive infrared radiation from a space in apassenger compartment of the vehicle occupied by the occupant. It canalso comprise an electric field sensor operative in a seat occupied bythe occupant or a capacitance sensor operative in a seat occupied by theoccupant. The implementation of such sensors in the invention will bereadily appreciated by one skilled in the art in view of the disclosureherein of general occupant sensors for sensing the position of theoccupant using waves, energy or radiation.

Looking now at FIG. 16, a schematic illustration of a system forcontrolling operation of a vehicle based on recognition of an authorizedindividual in accordance with the invention is shown. One or more imagesof the passenger compartment 105 are received at 106 and data derivedtherefrom at 107. Multiple image receivers may be provided at differentlocations. The data derivation may entail any one or more of numeroustypes of image processing techniques such as those described in U.S.Pat. No. 6,397,136 including those designed to improve the clarity ofthe image. A pattern recognition algorithm, e.g., a neural network, istrained in a training phase 108 to recognize authorized individuals. Thetraining phase can be conducted upon purchase of the vehicle by thedealer or by the owner after performing certain procedures provided tothe owner, e.g., entry of a security code or key. In the case of theoperator of a truck or when such an operator takes possession of atrailer or cargo container, the identity of the operator can be sent bytelematics to a central station for recording and perhaps furtherprocessing,

In the training phase for a theft prevention system, the authorizeddriver(s) would sit themselves in the driver or passenger seat andoptical images would be taken and processed to obtain the patternrecognition algorithm. A processor 109 is embodied with the patternrecognition algorithm thus trained to identify whether a person is theauthorized individual by analysis of subsequently obtained data derivedfrom optical images. The pattern recognition algorithm in processor 109outputs an indication of whether the person in the image is anauthorized individual for which the system is trained to identify. Asecurity system 110 enables operations of the vehicle when the patternrecognition algorithm provides an indication that the person is anindividual authorized to operate the vehicle and prevents operation ofthe vehicle when the pattern recognition algorithm does not provide anindication that the person is an individual authorized to operate thevehicle.

Optionally, an optical transmitting unit 111 is provided to transmitelectromagnetic energy into the passenger compartment, or other volumein the case of other vehicles, such that electromagnetic energytransmitted by the optical transmitting unit is reflected by the personand received by the optical image reception device 106.

As noted above, several different types of optical reception devices canbe used including a CCD array, a CMOS array, focal plane array (FPA),Quantum Well Infrared Photodetector (QWIP), any type of two-dimensionalimage receiver, any type of three-dimensional image receiver, an activepixel camera and an HDRC camera.

The processor 109 can be trained to determine the position of theindividuals included in the images obtained by the optical imagereception device, as well as the distance between the optical imagereception devices and the individuals.

Instead of a security system, another component in the vehicle can beaffected or controlled based on the recognition of a particularindividual. For example, the rear view mirror, seat, seat belt anchoragepoint, headrest, pedals, steering wheel, entertainment system, ridequality, air-conditioning/ventilation system can be adjusted.

Systems based on ultrasonics and neural networks have been verysuccessful in analyzing the seated-state of both the passenger anddriver seats of automobiles. Such systems are now going into productionfor preventing airbag deployment when a rear facing child seat or andout-of-position occupant is present. The ultrasonic systems, however,suffer from certain natural limitations that prevent system accuracyfrom getting better than about 99 percent. These limitations relate tothe fact that the wavelength of ultrasound is typically between 3 mm and8 mm. As a result, unexpected results occur which are due partially tothe interference of reflections from different surfaces. Additionally,commercially available ultrasonic transducers are tuned devices thatrequire several cycles before they transmit significant energy andsimilarly require several cycles before they effectively receive thereflected signals. This requirement has the effect of smearing theresolution of the ultrasound to the point that, for example, using aconventional 40 kHz transducer, the resolution of the system isapproximately three inches.

In contrast, the wavelength of near infrared is less than one micron andno significant interferences occur. Similarly, the system is not tunedand therefore is theoretically sensitive to a very few cycles. As aresult, resolution of the optical system is determined by the pixelspacing in the CCD or CMOS arrays. For this application, typical arrayshave been chosen to be 100 pixels by 100 pixels and therefore the spacebeing imaged can be broken up into pieces that are significantly lessthan 1 cm in size. Naturally, if greater resolution is required arrayshaving larger numbers of pixels are readily available. Another advantageof optical systems is that special lenses can be used to magnify thoseareas where the information is most critical and operate at reducedresolution where this is not the case. For example, the area closest tothe at-risk zone in front of the airbag can be magnified.

To summarize, although ultrasonic neural network systems are operatingwith high accuracy, they do not totally eliminate the problem of deathsand injuries caused by airbag deployments. Optical systems, on the otherhand, at little or no increase in cost, have the capability of virtually100 percent accuracy. Additional problems of ultrasonic systems arisefrom the slow speed of sound and diffraction caused by variations is airdensity. The slow sound speed limits the rate at which data can becollected and thus eliminates the possibility of tracking the motion ofan occupant during a high speed crash.

In an embodiment wherein electromagnetic energy is used, it is to beappreciated that any portion of the electromagnetic signals thatimpinges upon a body portion of the occupant is at least partiallyabsorbed by the body portion. Sometimes, this is due to the fact thatthe human body is composed primarily of water, and that electromagneticenergy at certain frequencies can be readily absorbed by water. Theamount of electromagnetic signal absorption is related to the frequencyof the signal, and size or bulk of the body portion that the signalimpinges upon. For example, a torso of a human body tends to absorb agreater percentage of electromagnetic energy as compared to a hand of ahuman body for some frequencies.

Thus, when electromagnetic waves or energy signals are transmitted by atransmitter, the returning waves received by a receiver provide anindication of the absorption of the electromagnetic energy. That is,absorption of electromagnetic energy will vary depending on the presenceor absence of a human occupant, the occupant's size, bulk, etc., so thatdifferent signals will be received relating to the degree or extent ofabsorption by the occupying item on a seat or elsewhere in the vehicle.The receiver will produce a signal representative of the returned wavesor energy signals which will thus constitute an absorption signal as itcorresponds to the absorption of electromagnetic energy by the occupyingitem in the seat.

Another optical infrared transmitter and receiver assembly is showngenerally at 52 in FIG. 5 and is mounted onto the instrument panelfacing the windshield. Although not shown in this view, reference 52consists of three devices, one transmitter and two receivers, one oneach side of the transmitter. In this case, the windshield is used toreflect the illumination light, and also the light reflected back by thedriver, in a manner similar to the “heads-up” display which is now beingoffered on several automobile models. The “heads-up” display, of course,is currently used only to display information to the driver and is notused to reflect light from the driver to a receiver. In this case, thedistance to the driver is determined stereoscopically through the use ofthe two receivers. In its most elementary sense, this system can be usedto measure the distance between the driver and the airbag module. Inmore sophisticated applications, the position of the driver, andparticularly of the driver's head, can be monitored over time and anybehavior, such as a drooping head, indicative of the driver fallingasleep or of being incapacitated by drugs, alcohol or illness can bedetected and appropriate action taken. Other forms of radiationincluding visual light, radar, terahertz and microwaves as well as highfrequency ultrasound could also be used by those skilled in the art.

A passive infrared system could be used to determine the position of anoccupant relative to an airbag or even to detect the presence of a humanor other life form in a vehicle. Passive infrared measures the infraredradiation emitted by the occupant and compares it to the background. Assuch, unless it is coupled with an imager and a pattern recognitionsystem, it can best be used to determine that an occupant is movingtoward the airbag since the amount of infrared radiation would then beincreasing. Therefore, it could be used to estimate the velocity of theoccupant but not his/her position relative to the airbag, since theabsolute amount of such radiation will depend on the occupant's size,temperature and clothes as well as on his position. When passiveinfrared is used in conjunction with another distance measuring system,such as the ultrasonic system described above, the combination would becapable of determining both the position and velocity of the occupantrelative to the airbag. Such a combination would be economical sinceonly the simplest circuits would be required. In one implementation, forexample, a group of waves from an ultrasonic transmitter could be sentto an occupant and the reflected group received by a receiver. Thedistance to the occupant would be proportional to the time between thetransmitted and received groups of waves and the velocity determinedfrom the passive infrared system. This system could be used in any ofthe locations illustrated in FIG. 5 as well as others not illustratedincluding truck trailers and cargo containers.

Recent advances in Quantum Well Infrared Photodetectors (QWIP) areparticularly applicable here due to the range of frequencies that theycan be designed to sense (3-18 microns) which encompasses the radiationnaturally emitted by the human body. Currently, QWIPs need to be cooledand thus are not quite ready for vehicle applications. There are,however, longer wave IR detectors based of focal plane arrays (FPA) thatare available in low resolution now. As the advantages of SWIR, MWIR andLWIR become more evident, devices that image in this part of theelectromagnetic spectrum will become more available.

Passive infrared could also be used effectively in conjunction with apattern recognition system. In this case, the passive infrared radiationemitted from an occupant can be focused onto a QWIP or FPA or even a CCDarray, in some cases, and analyzed with appropriate pattern recognitioncircuitry, or software, to determine the position of the occupant. Sucha system could be mounted at any of the preferred mounting locationsshown in FIG. 5 as well as others not illustrated.

Lastly, it is possible to use a modulated scanning beam of radiation anda single pixel receiver, PIN or avalanche diode, in the inventionsdescribed above. Any form of energy or radiation used above may also bein the infrared or radar spectrums and may be polarized and filters maybe used in the receiver to block out sunlight etc. These filters may benotch filters and may be made integral with the lens as one or morecoatings on the lens surface as is well known in the art. Note, in manyapplications, this may not be necessary as window glass blocks all IRexcept the near IR.

For some cases, such as a laser transceiver that may contain a CMOSarray, CCD, PIN or avalanche diode or other light sensitive devices, ascanner is also required that can be either solid state as in the caseof some radar systems based on a phased array, an acoustical opticalsystem as is used by some laser systems, or a mirror or MEMS basedreflecting scanner, or other appropriate technology.

1.3 Ultrasonics and Optics

In some cases, a combination of an optical system such as a camera andan ultrasonic system can be used. In this case, the optical system canbe used to acquire an image providing information as to the vertical andlateral dimensions of the scene and the ultrasound can be used toprovide longitudinal information, for example.

A more accurate acoustic system for determining the distance to aparticular object, or a part thereof, in the passenger compartment isexemplified by transducers 24 in FIG. 8E. In this case, three ultrasonictransmitter/receivers 24 are shown spaced apart mounted onto theA-pillar of the vehicle. Due to the wavelength, it is difficult to get anarrow beam using ultrasonics without either using high frequencies thathave limited range or a large transducer. A commonly available 40 kHztransducer, for example, is about 1 cm. in diameter and emits a sonicwave that spreads at about a sixty-degree angle. To reduce this anglerequires making the transducer larger in diameter. An alternate solutionis to use several transducers and to phase the transmissions from thetransducers so that they arrive at the intended part of the target inphase. Reflections from the selected part of the target are thenreinforced whereas reflections from adjacent parts encounterinterference with the result that the distance to the brightest portionwithin the vicinity of interest can be determined. A low-Q transducermay be necessary for this application.

By varying the phase of transmission from the three transducers 24, thelocation of a reflection source on a curved line can be determined. Inorder to locate the reflection source in space, at least one additionaltransmitter/receiver is required which is not co-linear with the others.The waves shown in FIG. 8E coming from the three transducers 24 areactually only the portions of the waves which arrive at the desiredpoint in space together in phase. The effective direction of these wavestreams can be varied by changing the transmission phase between thethree transmitters 24.

A determination of the approximate location of a point of interest onthe occupant can be accomplished by a CCD or CMOS array and appropriateanalysis and the phasing of the ultrasonic transmitters is determined sothat the distance to the desired point can be determined.

Although the combination of ultrasonics and optics has been described,it will now be obvious to others skilled in the art that other sensortypes can be combined with either optical or ultrasonic transducersincluding weight sensors of all types as discussed below, as well aselectric field, chemical, temperature, humidity, radiation, vibration,acceleration, velocity, position, proximity, capacitance, angular rate,heartbeat, radar, other electromagnetic, and other sensors.

1.4 Other Transducers

In FIG. 4, the ultrasonic transducers of the previous designs can bereplaced by laser or other electromagnetic wave transducers ortransceivers 8 and 9, which are connected to a microprocessor 20. Asdiscussed above, these are only illustrative mounting locations and anyof the locations described herein are suitable for particulartechnologies. Also, such electromagnetic transceivers are meant toinclude the entire electromagnetic spectrum including from X-rays to lowfrequencies where sensors such as capacitive or electric field sensorsincluding so called “displacement current sensors” as discussed indetail elsewhere herein, and the auto-tune antenna sensor also discussedherein operate.

2. Adaptation

Let us now consider the process of adapting a system of occupant orobject sensing transducers to a vehicle. For example, if a candidatesystem for an automobile consisting of eight transducers is considered,four ultrasonic transducers and four weight transducers, and if costconsiderations require the choice of a smaller total number oftransducers, it is a question of which of the eight transducers shouldbe eliminated. Fortunately, the neural network technology discussedbelow provides a technique for determining which of the eighttransducers is most important, which is next most important, etc. If thesix most critical transducers are chosen, that is the six transducerswhich contain or provide the most useful information as determined bythe neural network, a neural network can be trained using data fromthose six transducers and the overall accuracy of the system can bedetermined. Experience has determined, for example, that typically thereis almost no loss in accuracy by eliminating two of the eighttransducers, for example, two of the strain gage weight sensors. Aslight loss of accuracy occurs when one of the ultrasonic transducers isthen eliminated. In this manner, by the process of adaptation, the mostcost effective system can be determined from a proposed set of sensors.

This same technique can be used with the additional transducersdescribed throughout this disclosure. A transducer space can bedetermined with perhaps twenty different transducers comprised ofultrasonic, optical, electromagnetic, electric field, motion, heartbeat,weight, seat track, seatbelt payout, seatback angle and other types oftransducers depending on the particular vehicle application. The neuralnetwork can then be used in conjunction with a cost function todetermine the cost of system accuracy. In this manner, the optimumcombination of any system cost and accuracy level can be determined.

System Adaptation involves the process by which the hardwareconfiguration and the software algorithms are determined for aparticular vehicle. Each vehicle model or platform will most likely havea different hardware configuration and different algorithms. Some of thevarious aspects that make up this process are as follows:

-   -   The determination of the mounting location and aiming or        orientation of the transducers.    -   The determination of the transducer field angles or area or        volume monitored    -   The use of a combination neural network algorithm generating        program such as available from International Scientific        Research, Inc. to help generate the algorithms or other pattern        recognition algorithm generation program. (as described below)    -   The process of the collection of data in the vehicle, for        example, for neural network training purposes.    -   The method of automatic movement of the vehicle seats or other        structures or objects etc. while data is collected    -   The determination of the quantity of data to acquire and the        setups needed to achieve a high system accuracy, typically        several hundred thousand vectors or data sets.    -   The collection of data in the presence of varying environmental        conditions such as with thermal gradients.    -   The photographing of each data setup.    -   The makeup of the different databases and the use of typically        three different databases.    -   The method by which the data is biased to give higher        probabilities for, e.g., forward facing humans.    -   The automatic recording of the vehicle setup including seat,        seat back, headrest, window, visor, armrest, and other object        positions, for example, to help insure data integrity.    -   The use of a daily setup to validate that the transducer        configuration and calibration has not changed.    -   The method by which bad data is culled from the database.    -   The inclusion of the Fourier transforms and other pre-processors        of the data in the algorithm generation process if appropriate.    -   The use of multiple algorithm levels, for example, for        categorization and position.    -   The use of multiple algorithms in parallel.    -   The use of post processing filters and the particularities of        these filters.    -   The addition of fuzzy logic or other human intelligence based        rules.    -   The method by which data errors are corrected using, for        example, a neural network.    -   The use of a neural network generation program as the pattern        recognition algorithm generating system, if appropriate.    -   The use of back propagation neural networks for training.    -   The use of vector or data normalization.    -   The use of feature extraction techniques, for ultrasonic systems        for example, including:        -   The number of data points prior to a peak.        -   The normalization factor.        -   The total number of peaks.        -   The vector or data set mean or variance.    -   The use of feature extraction techniques, for optics systems for        example, including:        -   Motion.        -   Edge detection.        -   Feature detection such as the eyes, head etc.        -   Texture detection.        -   Recognizing specific features of the vehicle.        -   Line subtraction—i.e., subtracting one line of pixels from            the adjacent line with every other line illuminated. This            works primarily only with rolling shutter cameras. The            equivalent for a snapshot camera is to subtract an            artificially illuminated image from one that is illuminated            only with natural light.    -   The use of other computational intelligence systems such as        genetic algorithms    -   The use the data screening techniques.    -   The techniques used to develop stable networks including the        concepts of old and new networks.    -   The time spent or the number of iterations spent in, and method        of, arriving at stable networks.    -   The technique where a small amount of data is collected first        such as 16 sheets followed by a complete data collection        sequence.    -   The use of a cellular neural network for high speed data        collection and analysis when electromagnetic transducers are        used.    -   The use of a support vector machine.

The process of adapting the system to the vehicle begins with a surveyof the vehicle model. Any existing sensors, such as seat positionsensors, seat back sensors, door open sensors etc., are immediatecandidates for inclusion into the system. Input from the customer willdetermine what types of sensors would be acceptable for the finalsystem. These sensors can include: seat structure-mounted weightsensors, pad-type weight sensors, pressure-type weight sensors (e.g.,bladders), seat fore and aft position sensors, seat-mounted capacitance,electric field or antenna sensors, seat vertical position sensors, seatangular position sensors, seat back position sensors, headrest positionsensors, ultrasonic occupant sensors, optical occupant sensors,capacitive sensors, electric field sensors, inductive sensors, radarsensors, vehicle velocity and acceleration sensors, shock and vibrationsensors, temperature sensors, chemical sensors, radiation sensors, brakepressure, seatbelt force, payout and buckle sensors. accelerometers,gyroscopes, etc. A candidate array of sensors is then chosen and mountedonto the vehicle. At least one of the inventions disclosed hereincontemplates final systems including any such sensors or combinations ofsuch sensors, where appropriate, for the monitoring of the interiorand/or exterior of any vehicle as the term is defined above.

The vehicle can also be instrumented so that data input by humans isminimized. Thus, the positions of the various components in the vehiclesuch as the seats, windows, sun visor, armrest, etc. are automaticallyrecorded where possible. Also, the position of the occupant while datais being taken is also recorded through a variety of techniques such asdirect ultrasonic ranging sensors, optical ranging sensors, radarranging sensors, optical tracking sensors etc., where appropriate.Special cameras can also be installed to take one or more pictures ofthe setup to correspond to each vector of data collected or at someother appropriate frequency. Herein, a vector is used to represent a setof data collected at a particular epoch or representative of theoccupant or environment of vehicle at a particular point in time.

A standard set of vehicle setups is chosen for initial trial datacollection purposes. Typically, the initial trial will consist ofbetween 20,000 and 100,000 setups, although this range is not intendedto limit the invention.

Initial digital data collection now proceeds for the trial setup matrix.The data is collected from the transducers, digitized and combined toform to a vector of input data for analysis by a pattern recognitionsystem such as a neural network program or combination neural networkprogram. This analysis should yield a training accuracy of nearly 100%.If this is not achieved, then additional sensors are added to the systemor the configuration changed and the data collection and analysisrepeated. Note, in some cases the task is sufficiently simple that aneural network is not necessary, such as the determination that atrailer is not empty.

In addition to a variety of seating states for objects in the passengercompartment, for example, the trial database can also includeenvironmental effects such as thermal gradients caused by heat lamps andthe operation of the air conditioner and heater, or where appropriatelighting variations or other environmental variations that might affectparticular transducer types. A sample of such a matrix is presented inFIGS. 82A-82H of the '881 application, with some of the variables andobjects used in the matrix being designated or described in FIGS. 76-81Dfor automotive occupant sensing (of the '881 application). A similarmatrix can be generated for other vehicle monitoring applications suchas cargo containers and truck trailers. After the neural network hasbeen trained on the trial database, the trial database will be scannedfor vectors that yield erroneous results (which would likely beconsidered bad data). A study of those vectors along with vectors fromassociated in time cases are compared with the photographs to determinewhether there is erroneous data present. If so, an attempt is made todetermine the cause of the erroneous data. If the cause can be found,for example if a voltage spike on the power line corrupted the data,then the vector will be removed from the database and an attempt is madeto correct the data collection process so as to remove suchdisturbances.

At this time, some of the sensors may be eliminated from the sensormatrix. This can be determined during the neural network analysis, forexample, by selectively eliminating sensor data from the analysis to seewhat the effect if any results. Caution should be exercised here,however, since once the sensors have been initially installed in thevehicle, it requires little additional expense to use all of theinstalled sensors in future data collection and analysis.

The neural network, or other pattern recognition system, that has beendeveloped in this first phase can be used during the data collection inthe next phases as an instantaneous check on the integrity of the newvectors being collected.

The next set of data to be collected when neural networks are used, forexample, is the training database. This will usually be the largestdatabase initially collected and will cover such setups as listed, forexample, in FIGS. 82A-82H of the '881 application for occupant sensing.The training database, which may contain 500,000 or more vectors, willbe used to begin training of the neural network or other patternrecognition system. In the foregoing description, a neural network willbe used for exemplary purposes with the understanding that the inventionis not limited to neural networks and that a similar process exists forother pattern recognition systems. At least one of the inventionsdisclosed herein is largely concerned with the use of patternrecognition systems for vehicle internal monitoring. The best mode is touse trained pattern recognition systems such as neural networks. Whilethis is taking place, additional data will be collected according toFIGS. 78-80 and 83 of the independent and validation databases (of the'881 application).

The training database is usually selected so that it uniformly coversall seated states that are known to be likely to occur in the vehicle.The independent database may be similar in makeup to the trainingdatabase or it may evolve to more closely conform to the occupancy statedistribution of the validation database. During the neural networktraining, the independent database is used to check the accuracy of theneural network and to reject a candidate neural network design if itsaccuracy, measured against the independent database, is less than thatof a previous network architecture.

Although the independent database is not actually used in the trainingof the neural network, nevertheless, it has been found that itsignificantly influences the network structure or architecture.Therefore, a third database, the validation or real world database, isused as a final accuracy check of the chosen system. It is the accuracyagainst this validation database that is considered to be the systemaccuracy. The validation database is usually composed of vectors takenfrom setups which closely correlate with vehicle occupancy in realvehicles on the roadway or wherever they are used. Initially, thetraining database is usually the largest of the three databases. As timeand resources permit, the independent database, which perhaps starts outwith 100,000 vectors, will continue to grow until it becomesapproximately the same size or even larger than the training database.The validation database, on the other hand, will typically start outwith as few as 50,000 vectors. However, as the hardware configuration isfrozen, the validation database will continuously grow until, in somecases, it actually becomes larger than the training database. This isbecause near the end of the program, vehicles will be operating onhighways, ships, railroad tracks etc. and data will be collected in realworld situations. If in the real world tests, system failures arediscovered, this can lead to additional data being taken for both thetraining and independent databases as well as the validation database.

Once a neural network, or other pattern recognition system, has beentrained or otherwise developed using all of the available data from allof the transducers, it is expected that the accuracy of the network willbe very close to 100%. It is usually not practical to use all of thetransducers that have been used in the training of the system for finalinstallation in real production vehicle models. This is primarily due tocost and complexity considerations. Usually, the automobilemanufacturer, or other customer, will have an idea of how manytransducers would be acceptable for installation in a productionvehicle. For example, the data may have been collected using 20different transducers but the customer may restrict the final selectionto 6 transducers. The next process, therefore, is to gradually eliminatetransducers to determine what is the best combination of sixtransducers, for example, to achieve the highest system accuracy.Ideally, a series of neural networks, for example, would be trainedusing all combinations of six transducers from the 20 available. Theactivity would require a prohibitively long time. Certain constraintscan be factored into the system from the beginning to start the pruningprocess. For example, it would probably not make sense to have bothoptical and ultrasonic transducers present in the same system since itwould complicate the electronics. In fact, the customer may have decidedinitially that an optical system would be too expensive and thereforewould not be considered. The inclusion of optical transducers,therefore, serves as a way of determining the loss in accuracy as afunction of cost. Various constraints, therefore, usually allow theimmediate elimination of a significant number of the initial group oftransducers. This elimination and the training on the remainingtransducers provides the resulting accuracy loss that results.

The next step is to remove each of the transducers one at a time anddetermine which sensor has the least effect on the system accuracy. Thisprocess is then repeated until the total number of transducers has beenpruned down to the number desired by the customer. At this point, theprocess is reversed to add in one at a time those transducers that wereremoved at previous stages. It has been found, for example, that asensor that appears to be unimportant during the early pruning processcan become very important later on. Such a sensor may add a small amountof information due to the presence of various other transducers. Whereasthe various other transducers, however, may yield less information thanstill other transducers and, therefore may have been removed during thepruning process. Reintroducing the sensor that was eliminated early inthe cycle therefore can have a significant effect and can change thefinal choice of transducers to make up the system.

The above method of reducing the number of transducers that make up thesystem is but one of a variety approaches which have applicability indifferent situations. In some cases, a Monte Carlo or other statisticalapproach is warranted, whereas in other cases, a design of experimentsapproach has proven to be the most successful. In many cases, anoperator conducting this activity becomes skilled and after a whileknows intuitively what set of transducers is most likely to yield thebest results. During the process it is not uncommon to run multiplecases on different computers simultaneously. Also, during this process,a database of the cost of accuracy is generated. The automobilemanufacturer, for example, may desire to have the total of 6 transducersin the final system, however, when shown the fact that the addition ofone or two additional transducers substantially increases the accuracyof the system, the manufacturer may change his mind. Similarly, theinitial number of transducers selected may be 6 but the analysis couldshow that 4 transducers give substantially the same accuracy as 6 andtherefore the other 2 can be eliminated at a cost saving.

While the pruning process is occurring, the vehicle is subjected to avariety of real world tests and would be subjected to presentations tothe customer. The real world tests are tests that are run at differentlocations than where the fundamental training took place. It has beenfound that unexpected environmental factors can influence theperformance of the system and therefore these tests can provide criticalinformation. The system therefore, which is installed in the testvehicle, should have the capability of recording system failures. Thisrecording includes the output of all of the transducers on the vehicleas well as a photograph of the vehicle setup that caused the error. Thisdata is later analyzed to determine whether the training, independent orvalidation setups need to be modified and/or whether the transducers orpositions of the transducers require modification.

Once the final set of transducers in some cases is chosen, the vehicleis again subjected to real world testing on highways, or wherever it iseventually to be used, and at customer demonstrations. Once again, anyfailures are recorded. In this case, however, since the total number oftransducers in the system is probably substantially less than theinitial set of transducers, certain failures are to be expected. Allsuch failures, if expected, are reviewed carefully with the customer tobe sure that the customer recognizes the system failure modes and isprepared to accept the system with those failure modes.

The system described so far has been based on the use of a single neuralnetwork or other pattern recognition system. It is frequently necessaryand desirable to use combination neural networks, multiple neuralnetworks, cellular neural networks or support vector machines or otherpattern recognition systems. For example, for determining the occupancystate of a vehicle seat or other part of the vehicle, there may be atleast two different requirements. The first requirement is to establishwhat is occupying the seat, for example, and the second requirement isto establish where that object is located. Another requirement might beto simply determine whether an occupying item warranting analysis by theneural networks is present. Generally, a great deal of time, typicallymany seconds, is available for determining whether a forward facinghuman or an occupied or unoccupied rear facing child seat, for example,occupies a vehicle seat. On the other hand, if the driver of the vehicleis trying to avoid an accident and is engaged in panic braking, theposition of an unbelted occupant can be changing rapidly as he or she ismoving toward the airbag. Thus, the problem of determining the locationof an occupant is time critical. Typically, the position of the occupantin such situations must be determined in less than 20 milliseconds.There is no reason for the system to have to determine that a forwardfacing human being is in the seat while simultaneously determining wherethat forward facing human being is. The system already knows that theforward facing human being is present and therefore all of the resourcescan be used to determine the occupant's position. Thus, in thissituation, a dual level or modular neural network can be advantageouslyused. The first level determines the occupancy of the vehicle seat andthe second level determines the position of that occupant. In somesituations, it has been demonstrated that multiple neural networks usedin parallel can provide some benefit. This will be discussed in moredetail below. Both modular and multiple parallel neural networks areexamples of combination neural networks.

The data fed to the pattern recognition system will usually not be theraw vectors of data as captured and digitized from the varioustransducers. Typically, a substantial amount of preprocessing of thedata is undertaken to extract the important information from the datathat is fed to the neural network. This is especially true in opticalsystems and where the quantity of data obtained, if all were used by theneural network, would require very expensive processors. The techniquesof preprocessing data will not be described in detail here. However, thepreprocessing techniques influence the neural network structure in manyways. For example, the preprocessing used to determine what is occupyinga vehicle seat is typically quite different from the preprocessing usedto determine the location of that occupant. Some particularpreprocessing concepts will be discussed in more detail below.

A pattern recognition system, such as a neural network, can sometimesmake irrational decisions. This typically happens when the patternrecognition system is presented with a data set or vector that is unlikeany vector that has been in its training set. The variety of seatingstates of a vehicle is unlimited. Every attempt is made to select fromthat unlimited universe a set of representative cases. Nevertheless,there will always be cases that are significantly different from anythat have been previously presented to the neural network. The finalstep, therefore, to adapting a system to a vehicle, is to add a measureof human intelligence or common sense. Sometimes this goes under theheading of fuzzy logic and the resulting system has been termed in somecases, a neural fuzzy system. In some cases, this takes the form of anobserver studying failures of the system and coming up with rules andthat say, for example, that if transducer A perhaps in combination withanother transducer produces values in this range, then the system shouldbe programmed to override the pattern recognition decision andsubstitute therefor a human decision.

An example of this appears in R. Scorcioni, K. Ng, M. M. Trivedi, N.Lassiter; “MoNiF: A Modular Neuro-Fuzzy Controller for Race CarNavigation”; in Proceedings of the 1997 IEEE Symposium on ComputationalIntelligence and Robotics Applications, Monterey, Calif., USA July 1997,which describes the case of where an automobile was designed forautonomous operation and trained with a neural network, in one case, anda neural fuzzy system in another case. As long as both vehicles operatedon familiar roads both vehicles performed satisfactorily. However, whenplaced on an unfamiliar road, the neural network vehicle failed whilethe neural fuzzy vehicle continued to operate successfully. Naturally,if the neural network vehicle had been trained on the unfamiliar road,it might very well have operated successful. Nevertheless, the criticalfailure mode of neural networks that most concerns people is thisuncertainty as to what a neural network will do when confronted with anunknown state.

One aspect, therefore, of adding human intelligence to the system, is toferret out those situations where the system is likely to fail.Unfortunately, in the current state-of-the-art, this is largely a trialand error activity. One example is that if the range of certain parts ofvector falls outside of the range experienced during training, thesystem defaults to a particular state. In the case of suppressingdeployment of one or more airbags, or other occupant protectionapparatus, this case would be to enable airbag deployment even if thepattern recognition system calls for its being disabled. An alternatemethod is to train a particular module of a modular neural network torecognize good from bad data and reject the bad data before it is fed tothe main neural networks.

The foregoing description is applicable to the systems described in thefollowing drawings and the connection between the foregoing descriptionand the systems described below will be explained below. However, itshould be appreciated that the systems shown in the drawings do notlimit the applicability of the methods or apparatus described above.

Referring again to FIG. 6, and to FIG. 6A which differs from FIG. 6 onlyin the use of a strain gage weight sensor mounted within the seatcushion, motion sensor 73 can be a discrete sensor that detects relativemotion in the passenger compartment of the vehicle. Such sensors arefrequently based on ultrasonics and can measure a change in theultrasonic pattern that occurs over a short time period. Alternately,the subtracting of one position vector from a previous position vectorto achieve a differential position vector can detect motion. For thepurposes herein, a motion sensor will be used to mean either aparticular device that is designed to detect motion for the creation ofa special vector based on vector differences or a neural network trainedto determine motion based on successive vectors.

An ultrasonic, optical or other sensor or transducer system 9 can bemounted on the upper portion of the front pillar, i.e., the A-Pillar, ofthe vehicle and a similar sensor system 6 can be mounted on the upperportion of the intermediate pillar, i.e., the B-Pillar. Each sensorsystem 6, 9 may comprise a transducer. The outputs of the sensor systems6 and 9 can be input to a band pass filter 60 through a multiplexcircuit 59 which can be switched in synchronization with a timing signalfrom the ultrasonic sensor drive circuit 58, for example, and then canbe amplified by an amplifier 61. The band pass filter 60 removes a lowfrequency wave component from the output signal and also removes some ofthe noise. The envelope wave signal can be input to an analog/digitalconverter (ADC) 62 and digitized as measured data. The measured data canbe input to a processing circuit 63, which can be controlled by thetiming signal which can be in turn output from the sensor drive circuit58. The above description applies primarily to systems based onultrasonics and will differ somewhat for optical, electric field andother systems and for different vehicle types.

Each of the measured data can be input to a normalization circuit 64 andnormalized. The normalized measured data can be input to the combinationneural network (circuit) 65, for example, as wave data.

The output of the pressure or weight sensor(s) 7, 76 or 97 (see FIG. 6A)can be amplified by an amplifier 66 coupled to the pressure or weightsensor(s) 7, 76 and 97 and the amplified output can be input to ananalog/digital converter and then directed to the neural network 65, forexample, of the processor means. Amplifier 66 can be useful in someembodiments but it may be dispensed with by constructing the sensors 7,76, 97 to provide a sufficiently strong output signal, and even possiblya digital signal. One manner to do this would be to construct the sensorsystems with appropriate electronics.

The neural network 65 can be directly connected to the ADCs 68 and 69,the ADC associated with amplifier 66 and the normalization circuit 64.As such, information from each of the sensors in the system (a stream ofdata) can be passed directly to the neural network 65 for processingthereby. The streams of data from the sensors are usually not combinedprior to the neural network 65 and the neural network 65 can be designedto accept the separate streams of data (e.g., at least a part of thedata at each input node) and process them to provide an outputindicative of the current occupancy state of the seat or of the vehicle.The neural network 65 thus includes or incorporates a plurality ofalgorithms derived by training in the manners discussed herein. Once thecurrent occupancy state of the seat or vehicle is determined, it ispossible to control vehicular components or systems, such as the airbagsystem or telematics system, in consideration of the current occupancystate of the seat or vehicle.

A discussion of the methodology of adapting a monitoring system to anautomotive vehicle for the purpose primarily of controlling a componentsuch as a restraint system is disclosed in the '881 application withreference to FIGS. 28-36. Generally simpler systems are used for cargocontainer, truck trailer and other vehicle monitoring cases.

In addition to variations in occupancy or seated states, it is importantto consider environmental effects during the data collection. Thermalgradients or thermal instabilities are particularly important forsystems based on ultrasound since sound waves can be significantlydiffracted by density changes in air. There are two aspects of the useof thermal gradients or instability in training. First, the fact thatthermal instabilities exist and therefore data with thermalinstabilities present should be part of database. For this case, arather small amount of data collected with thermal instabilities wouldbe used. A much more important use of thermal instability comes from thefact that they add variability to data. Thus, considerably more data istaken with thermal instability and in fact, in some cases a substantialpercentage of the database is taken with time varying thermal gradientsin order to provide variability to the data so that the neural networkdoes not memorize but instead generalizes from the data. This isaccomplished by taking the data with a cold vehicle with the heateroperating and with a hot vehicle with the air conditioner operating, forexample. Additional data is also taken with a heat lamp in a closedvehicle to simulate a stable thermal gradient caused by sun loading.

To collect data for 500,000 vehicle configurations is not a formidabletask. A trained technician crew can typically collect data on in excesson 2000 configurations or vectors per hour. The data is collectedtypically every 50 to 100 milliseconds. During this time, the occupantis continuously moving, assuming a continuously varying position andposture in the vehicle including moving from side to side, forward andback, twisting his/her head, reading newspapers and books, moving hands,arms, feet and legs, until the desired number of different seated stateexamples are obtained. In some cases, this process is practiced byconfining the motion of an occupant into a particular zone. In somecases, for example, the occupant is trained to exercise these differentseated state motions while remaining in a particular zone that may bethe safe zone, the keep out zone, or an intermediate gray zone. In thismanner, data is collected representing the airbag disable, depoweredairbag-enabled or full power airbag-enabled states. In other cases, theactual position of the back of the head and/or the shoulders of theoccupant are tracked using string pots, high frequency ultrasonictransducers, optically, by RF or other equivalent methods. In thismanner, the position of the occupant can be measured and the decision asto whether this should be a disable or enable airbag case can be decidedlater. By continuously monitoring the occupant, an added advantageresults in that the data can be collected to permit a comparison of theoccupant from one seated state to another. This is particularly valuablein attempting to project the future location of an occupant based on aseries of past locations as would be desirable for example to predictwhen an occupant would cross into the keep out zone during a panicbraking situation prior to crash.

It is important to note that it is not necessary to tailor the systemfor every vehicle produced but rather to tailor it for each model orplatform. However, a neural network, and especially a combination neuralnetwork, can be designed with some adaptability to compensate forvehicle to vehicle differences within a platform such as mountingtolerances, or to changes made by the owner or due to aging. A platformis an automobile manufacturer's designation of a group of vehicle modelsthat are built on the same vehicle structure. A model would also applyto a particular size, shape or geometry of truck trailer or cargocontainer The methods above have been described mainly in connectionwith the use of ultrasonic transducers. Many of the methods, however,are also applicable to optical, radar, capacitive, electric field andother sensing systems and where applicable, at least one of theinventions disclosed herein is not limited to ultrasonic systems. Inparticular, an important feature of at least one of the inventionsdisclosed herein is the proper placement of two or more separatelylocated receivers such that the system still operates with highreliability if one of the receivers is blocked by some object such as anewspaper or box. This feature is also applicable to systems usingelectromagnetic radiation instead of ultrasonic, however the particularlocations will differ based on the properties of the particulartransducers. Optical sensors based on two-dimensional cameras or otherimage sensors, for example, are more appropriately placed on the sidesof a rectangle surrounding the seat to be monitored, for the automotivevehicle case, rather than at the corners of such a rectangle as is thecase with ultrasonic sensors. This is because ultrasonic sensors measurean axial distance from the sensor where the 2D camera is mostappropriate for measuring distances up and down and across its fieldview rather than distances to the object. With the use ofelectromagnetic radiation and the advances which have recently been madein the field of very low light level sensitivity, it is now possible, insome implementations, to eliminate the transmitters and use backgroundlight as the source of illumination along with using a technique such asauto-focusing or stereo vision to obtain the distance from the receiverto the object. Thus, only receivers would be required further reducingthe complexity of the system.

Although implicit in the above discussion, an important feature of atleast one of the inventions disclosed herein which should be emphasizedis the method of developing a system having distributed transducermountings. Other systems which have attempted to solve the rear facingchild seat (RFCS) and out-of-position problems have relied on a singletransducer mounting location or at most, two transducer mountinglocations. Such systems can be easily blinded by a newspaper or by thehand of an occupant, for example, which is imposed between the occupantand the transducers. This problem is almost completely eliminatedthrough the use of three or more transducers which are mounted so thatthey have distinctly different views of the passenger compartment volumeof interest. If the system is adapted using four transducers, forexample, the system suffers only a slight reduction in accuracy even iftwo of the transducers are covered so as to make them inoperable.However, the automobile manufacturers may not wish to pay the cost ofseveral different mounting locations and an alternate is to mount thesensors high where blockage is difficult and to diagnose whether ablockage state exists.

It is important in order to obtain the full advantages of the systemwhen a transducer is blocked, that the training and independentdatabases contains many examples of blocked transducers. If the patternrecognition system, the neural network in this case, has not beentrained on a substantial number of blocked transducer cases, it will notdo a good job in recognizing such cases later. This is yet anotherinstance where the makeup of the databases is crucial to the success ofdesigning the system that will perform with high reliability in avehicle and is an important aspect of the instant invention. Whencamera-based transducers are used, for example, an alternative strategyis to diagnose when a newspaper or other object is blocking a camera,for example. In most cases, a short time blockage is of littleconsequence since earlier decisions provide the seat occupancy and thedecision to enable deployment or suppress deployment of the occupantrestraint will not change. For a prolonged blockage, the diagnosticsystem can provide a warning light indicating to the driver, operator orother interested party which may be remote from the vehicle, that thesystem is malfunctioning and the deployment decision is again either notchanged or changed to the default decision, which is usually to enabledeployment for the automobile occupant monitoring case.

Specific issues relating to transducers are discussed more fully in theparent application.

It is important to realize that the adaptation process described hereinapplies to any combination of transducers that provide information aboutthe vehicle occupancy. These include weight sensors, capacitive sensors,electric field sensors, inductive sensors, moisture sensors, chemicalsensors, ultrasonic, radiation, optic, infrared, radar, X-ray amongothers. The adaptation process begins with a selection of candidatetransducers for a particular vehicle model. This selection is based onsuch considerations as cost, alternate uses of the system other thanoccupant sensing, vehicle interior compartment geometry, desiredaccuracy and reliability, vehicle aesthetics, vehicle manufacturerpreferences, and others. Once a candidate set of transducers has beenchosen, these transducers are mounted in the test vehicle according tothe teachings of at least one of the inventions disclosed herein. Thevehicle is then subjected to an extensive data collection processwherein various objects are placed in the vehicle at various locationsas described below and an initial data set is collected. A patternrecognition system is then developed using the acquired data and anaccuracy assessment is made. Further studies are made to determinewhich, if any, of the transducers can be eliminated from the design. Ingeneral, the design process begins with a surplus of sensors plus anobjective as to how many sensors are to be in the final vehicleinstallation. The adaptation process can determine which of thetransducers are most important and which are least important and theleast important transducers can be eliminated to reduce system cost andcomplexity.

A process for adapting an ultrasonic system to a vehicle will now bedescribed. Note, some steps will not apply to some vehicles. A moredetailed list of steps is provided in Appendix 2 of U.S. patentapplication Ser. No. 10/940,811 incorporated by reference herein.Although the pure ultrasonic system is described here for automotiveapplications, a similar or analogous set of steps applies for othervehicle types and when other technologies such as weight and optical(scanning or imager) or other electromagnetic wave or electric fieldsystems such as capacitance and field monitoring systems are used. Thisdescription is thus provided to be exemplary and not limiting:

1. Select transducer, horn and grill designs to fit the vehicle. At thisstage, usually full horns are used which are mounted so that theyproject into the compartment. No attempt is made at this time to achievean esthetic matching of the transducers to the vehicle surfaces. Anestimate of the desired transducer fields is made at this time eitherfrom measurements in the vehicle directly or from CAD drawings.

2. Make polar plots of the transducer ultrasonic fields. Transducers andcandidate horns and grills are assembled and tested to confirm that thedesired field angles have been achieved. This frequently requires someadjustment of the transducers in the horn and of the grill. A properlydesigned grill for ultrasonic systems can perform a similar function asa lens for optical systems.

3. Check to see that the fields cover the required volumes of thevehicle passenger compartment and do not impinge on adjacent flatsurfaces that may cause multipath effects. Redesign horns and grills ifnecessary.

4. Install transducers into vehicle.

5. Map transducer fields in the vehicle and check for multipath effectsand proper coverage.

6. Adjust transducer aim and re-map fields if necessary.

7. Install daily calibration fixture and take standard setup data.

8. Acquire 50,000 to 100,000 vectors of data

9. Adjust vectors for volume considerations by removing some initialdata points if cross talk or ringing is present and some final points tokeep data in the desired passenger compartment volume.

10. Normalize vectors.

11. Run neural network algorithm generating software to create algorithmfor vehicle installation.

12. Check the accuracy of the algorithm. If not sufficiently accuratecollect more data where necessary and retrain. If still not sufficientlyaccurate, add additional transducers to cover holes.

13. When sufficient accuracy is attained, proceed to collect ˜500,000training vectors varying:

-   -   Occupancy (see Appendices 1 and 3 of U.S. patent application        Ser. No. 10/940,881 incorporated by reference herein):    -   Occupant size, position (zones), clothing etc Child seat type,        size, position etc.    -   Empty seat    -   Vehicle configuration:    -   Seat position    -   Window position    -   Visor and armrest position    -   Presence of other occupants in adjoining seat or rear seat    -   Temperature    -   Temperature gradient—stable    -   Temperature turbulence—heater and air conditioner    -   Wind turbulence—High speed travel with windows open, top down        etc.    -   Other similar features when the adaptation is to a vehicle other        than an automobile.

14. Collect ˜100,000 vectors of Independent data using othercombinations of the above

15. Collect ˜50,000 vectors of “real world data” to represent theacceptance criteria and more closely represent the actual seated stateprobabilities in the real world.

16. Train network and create an algorithm using the training vectors andthe Independent data vectors.

17. Validate the algorithm using the real world vectors.

18. Install algorithm into the vehicle and test.

19. Decide on post processing methodology to remove final holes (areasof inaccuracy) in system

20. Implement post-processing methods into the algorithm

21. Final test. The process up until step 13 involves the use oftransducers with full horns mounted on the surfaces of the interiorpassenger compartment. At some point, the actual transducers which areto be used in the final vehicle must be substituted for the trialtransducers. This is either done prior to step 13 or at this step. Thisprocess involves designing transducer holders that blend with the visualsurfaces of the vehicle compartment so that they can be covered with aproperly designed grill that helps control the field and also serves toretain the esthetic quality of the interior. This is usually a lengthyprocess and involves several consultations with the customer. Usually,therefore, the steps from 13-20 are repeated at this point after thefinal transducer and holder design has been selected. The initial datataken with full horns gives a measure of the best system that can bemade to operate in the vehicle. Some degradation in performance isexpected when the aesthetic horns and grills are substituted for thefull horns. By conducting two complete data collection cycles, anaccurate measure of this accuracy reduction can be obtained.

22. Up until this point, the best single neural network algorithm hasbeen developed. The final step is to implement the principles of acombination neural network in order to remove some remaining errorsources such as bad data and to further improve the accuracy of thesystem. It has been found that the implementation of combination neuralnetworks can reduce the remaining errors by up to 50 percent. Acombination neural network CAD optimization program provided byInternational Scientific Research Inc. can now be used to derive theneural network architecture. Briefly, the operator lays out acombination neural network involving many different neural networksarranged in parallel and in series and with appropriate feedbacks whichthe operator believes could be important. The software then optimizeseach neural network and also provides an indication of the value of thenetwork. The operator can then selectively eliminate those networks withlittle or no value and retrain the system. Through this combination ofpruning, retraining and optimizing the final candidate combinationneural network results.

23. Ship to customers to be used in production vehicles.

24. Collect additional real world validation data for continuousimprovement.

More detail on the operation of the transducers and control circuitry aswell as the neural network is provided in the above-referenced patentsand patent applications and elsewhere herein. One particular example ofa successful neural network for the two transducer case had 78 inputnodes, 6 hidden nodes and 1 output node and for the four transducer casehad 176 input nodes 20 hidden layer nodes on hidden layer one, 7 hiddenlayer nodes on hidden layer two and 1 output node. The weights of thenetwork were determined by supervised training using the backpropagation method as described in the above-referenced patents andpatent applications and in more detail in the references cited therein.Other neural network architectures are possible including RCE, LogiconProjection, Stochastic, cellular, or support vector machine, etc. Anexample of a combination neural network system is shown in FIG. 37 ofthe '881 application, incorporated by reference herein. Any of thenetwork architectures mention here can be used for any of the boxes inFIG. 37.

Finally, the system is trained and tested with situations representativeof the manufacturing and installation tolerances that occur during theproduction and delivery of the vehicle as well as usage anddeterioration effects. Thus, for example, the system is tested with thetransducer mounting positions shifted by up to one inch in any directionand rotated by up to 5 degrees, with a simulated accumulation of dirtand other variations. This tolerance to vehicle variation also sometimespermits the installation of the system onto a different but similarmodel vehicle with, in many cases, only minimal retraining of thesystem.

3. Mounting Locations for and Quantity of Transducers

Ultrasonic transducers are relatively good at measuring the distancealong a radius to a reflective object. An optical array, to be discussednow, on the other hand, can get accurate measurements in two dimensions,the lateral and vertical dimensions relative to the transducer. Assumingthe optical array has dimensions of 100 by 100 as compared to anultrasonic sensor that has a single dimension of 100, an optical arraycan therefore provide 100 times more information than the ultrasonicsensor. Most importantly, this vastly greater amount of information doesnot cost significantly more to obtain than the information from theultrasonic sensor.

As illustrated in FIGS. 8A-8D, the optical sensors are typically locatedfor an automotive vehicle at the positions where the desired informationis available with the greatest resolution. These positions are typicallyin the center front and center rear of the occupancy seat and at thecenter on each side and top. This is in contrast to the optimum locationfor ultrasonic sensors, which are the corners of such a rectangle thatoutlines the seated volume. Styling and other constraints often preventmounting of transducers at the optimum locations.

An optical infrared transmitter and receiver assembly is shown generallyat 52 in FIG. 8B and is mounted onto the instrument panel facing thewindshield. Assembly 52 can either be recessed below the upper face ofthe instrument panel or mounted onto the upper face of the instrumentpanel. Assembly 52, shown enlarged, comprises a source of infraredradiation, or another form of electromagnetic radiation, and a CCD, CMOSor other appropriate arrays of typically 160 pixels by 160 pixels. Inthis embodiment, the windshield is used to reflect the illuminationlight provided by the infrared radiation toward the objects in thepassenger compartment and also reflect the light being reflected back bythe objects in the passenger compartment, in a manner similar to the“heads-up” display which is now being offered on several automobilemodels. The “heads-up” display, of course, is currently used only todisplay information to the driver and is not used to reflect light fromthe driver to a receiver. Once again, unless one of the distancemeasuring systems as described below is used, this system alone cannotbe used to determine distances from the objects to the sensor. Its mainpurpose is object identification and monitoring. Depending on theapplication, separate systems can be used for the driver and for thepassenger. In some cases, the cameras located in the instrument panelwhich receive light reflected off of the windshield can be co-locatedwith multiple lenses whereby the respective lenses aimed at the driverand passenger seats respectively.

Assembly 52 is actually about two centimeters or less in diameter and isshown greatly enlarged in FIG. 8B. Also, the reflection area on thewindshield is considerably smaller than illustrated and specialprovisions are made to assure that this area of the windshield is flatand reflective as is done generally when heads-up displays are used. Forcases where there is some curvature in the windshield, it can be atleast partially compensated for by the CCD optics.

Transducers 23-25 are illustrated mounted onto the A-pillar of thevehicle, however, since these transducers are quite small, typicallyless than 2 cm on a side, they could alternately be mounted onto thewindshield itself, or other convenient location which provides a clearview of the portion of the passenger compartment being monitored. Otherpreferred mounting locations include the headliner above and also theside of the seat. Some imagers are now being made that are less than 1cm on a side.

In the preferred implementation, as shown in FIGS. 8A-8E, fourtransducer assemblies are positioned around the seat to be monitored,each can comprise one or more LEDs with a diverging lenses and a CMOSarray. Although illustrated together, the illuminating source in manycases will not be co-located with the receiving array. The LED emits acontrolled angle, 120° for example, diverging cone of infrared radiationthat illuminates the occupant from both sides and from the front andrear. This angle is not to be confused with the field angle used inultrasonic systems. With ultrasound, extreme care is required to controlthe field of the ultrasonic waves so that they will not create multipatheffects and add noise to the system. With infrared, there is no reason,in the implementation now being described, other than to make the mostefficient use of the infrared energy, why the entire vehicle cannot beflooded with infrared energy either from many small sources or from afew bright ones.

The image from each array is used to capture two dimensions of occupantposition information, thus, the array of assembly 50 positioned on thewindshield header, which is approximately 25% of the way laterallyacross the headliner in front of the driver, provides a both verticaland transverse information on the location of the driver. A similar viewfrom the rear is obtained from the array of assembly 54 positionedbehind the driver on the roof of the vehicle and above the seatbackpotion of the seat 72. As such, assembly 54 also provides both verticaland transverse information on the location of the driver. Finally,arrays of assemblies 49 and 51 provide both vertical and longitudinaldriver location information. Another preferred location is the headlinercentered directly above the seat of interest. The position of theassemblies 49-52 and 54 may differ from that shown in the drawings. Inthe invention, in order that the information from two or more of theassemblies 49-52 and 54 may provide a three-dimensional image of theoccupant, or portion of the passenger compartment, the assembliesgenerally should not be arranged side-by-side. A side-by-sidearrangement as used in several prior art references discussed above,will provide two essentially identical views with the difference being alateral shift. This does not enable a complete three-dimensional view ofthe occupant.

One important point concerns the location and number of opticalassemblies. It is possible to use fewer than four such assemblies with apossible resulting loss in accuracy. The number of four was chosen sothat either a forward or rear assembly or either of the side assembliescan be blocked by a newspaper, for example, without seriously degradingthe performance of the system. Since drivers rarely are readingnewspapers while driving, fewer than four arrays are usually adequatefor the driver side. In fact, one is frequently sufficient. One camerais also usually sufficient for the passenger side if the goal of thesystem is classification only or if camera blockage is tolerated foroccupant tracking.

The particular locations of the optical assemblies were chosen to givethe most accurate information as to the locations of the occupant. Thisis based on an understanding of what information can be best obtainedfrom a visual image. There is a natural tendency on the part of humansto try to gauge distance from the optical sensors directly. This, as canbe seen above, is at best complicated involving focusing systems,stereographic systems, multiple arrays and triangulation, time of flightmeasurement, etc. What is not intuitive to humans is to not try toobtain this distance directly from apparatus or techniques associatedwith the mounting location. Whereas ultrasound is quite good formeasuring distances from the transducer (the z-axis), optical systemsare better at measuring distances in the vertical and lateral directions(the x and y-axes). Since the precise locations of the opticaltransducers are known, that is, the geometry of the transducer locationsis known relative to the vehicle, there is no need to try to determinethe displacement of an object of interest from the transducer (thez-axis) directly. This can more easily be done indirectly by anothertransducer. That is, the vehicle z-axis to one transducer is the camerax-axis to another.

Another preferred location of a transmitter/receiver 54 for use withairbags is attached to the steering wheel (see FIG. 5) and gives anaccurate determination of the distance of the driver's chest from theairbag module. This implementation would generally be used with anotherdevice such as 50 at another location. Details about mounting atransmitter/receiver on a cover of an airbag module are set forth in the'881 application.

One problem of the system using a transmitter/receiver on an airbagcover as shown in FIG. 5 is that a driver may have inadvertently placedhis hand over the transmitter/receiver 54, thus defeating the operationof the device. A second confirming transmitter/receiver 50 can thereforebe placed at some other convenient position such as on the roof orheadliner of the passenger compartment as shown in FIG. 5. Thistransmitter/receiver 50 operates in a manner similar totransmitter/receiver 54.

The applications described herein have been illustrated using the driverof the vehicle. The same systems of determining the position of theoccupant relative to the airbag apply to the passenger, sometimesrequiring minor modifications. Also of course, a similar system can beappropriately designed for other monitoring situations such as for cargocontainers and truck trailers.

It is likely that the sensor required triggering time based on theposition of the occupant will be different for the driver than for thepassenger. Current systems are based primarily on the driver with theresult that the probability of injury to the passenger is necessarilyincreased either by deploying the airbag too late or by failing todeploy the airbag when the position of the driver would not warrant itbut the passenger's position would. With the use of occupant positionsensors for both the passenger and driver, the airbag system can beindividually optimized for each occupant and result in furthersignificant injury reduction. In particular, either the driver orpassenger system can be disabled if either the driver or passenger isout of position.

There is almost always a driver present in vehicles that are involved inaccidents where an airbag is needed. Only about 30% of these vehicles,however, have a passenger. If the passenger is not present, there isusually no need to deploy the passenger side airbag. The occupantposition sensor, when used for the passenger side with proper patternrecognition circuitry, can also ascertain whether or not the seat isoccupied, and if not, can disable the deployment of the passenger sideairbag and thereby save the cost of its replacement. A sophisticatedpattern recognition system could even distinguish between an occupantand a bag of groceries or a box, for example, which in some cargocontainer or truck trailer monitoring situations is desired. Finally,there has been much written about the out of position child who isstanding or otherwise positioned adjacent to the airbag, perhaps due topre-crash braking. The occupant position sensor described herein canprevent the deployment of the airbag in this situation.

3.1 Single Camera, Dual Camera with Single Light Source

Many automobile companies are opting to satisfy the requirements ofFMVSS-208 by using a weight only system such as the bladder or straingage systems disclosed here. Such a system provides an elementarymeasure of the weight of the occupying object but does not give areliable indication of its position, at least for automotive vehicles.It can also be easily confused by any object that weighs 60 or morepounds and that is interpreted as an adult. Weight only systems are alsostatic systems in that due to vehicle dynamics that frequently accompanya pre crash braking event they are unable to track the position of theoccupant. The load from seatbelts can confuse the system and therefore aspecial additional sensor must be used to measure seatbelt tension. Insome systems, the device must be calibrated for each vehicle and thereis some concern as to whether this calibration will be proper for thelife on the vehicle.

A single camera can frequently provide considerably more informationthan a weight only system without the disadvantages of weight sensorsand do so at a similar cost. Such a single camera in its simplestinstallation can categorize the occupancy state of the vehicle anddetermine whether the airbag should be suppressed due to an empty seator the presence of a child of a size that corresponds to one weighingless than 60 pounds. Of course, a single camera can also easily doconsiderably more by providing a static out-of-position indication and,with the incorporation of a faster processor, dynamic out-of-positiondetermination can also be provided. Thus, especially with the costs ofmicroprocessors continuing to drop, a single camera system can easilyprovide considerably more functionality than a weight only system andyet stay in the same price range.

A principal drawback of a single camera system is that it can be blockedby the hand of an occupant or by a newspaper, for example. This is arare event since the preferred mounting location for the camera istypically high in the vehicle such as on the headliner. Also, it isconsiderably less likely that the occupant will always be reading anewspaper, for example, and if he or she is not reading it when thesystem is first started up, or at any other time during the trip, thecamera system will still get an opportunity to see the occupant when heor she is not being blocked and make the proper categorization. Theability of the system to track the occupant will be impaired but thesystem can assume that the occupant has not moved toward the airbagwhile reading the newspaper and thus the initial position of theoccupant can be retained and used for suppression determination.Finally, the fact that the camera is blocked can be determined and thedriver made aware of this fact in much the same manner that a seatbeltlight notifies the driver that the passenger is not wearing his or herseatbelt.

The accuracy of a single camera system can be above 99% whichsignificantly exceeds the accuracy of weight only systems. Nevertheless,some automobile manufacturers desire even greater accuracy and thereforeopt for the addition of a second camera. Such a camera is usually placedon the opposite side of the occupant as the first camera. The firstcamera may be placed on or near the dome light, for example, and thesecond camera can be on the headliner above the side door. A dual camerasystem such as this can operate more accurately in bright daylightsituations where the window area needs to be ignored in the view of thecamera that is mounted near the dome.

Sometimes, in a dual camera system, only a single light source is used.This provides a known shadow pattern for the second camera and helps toaccentuate the edges of the occupying item rendering classificationeasier. Any of the forms of structured light can also be used andthrough these and other techniques the corresponding points in the twoimages can more easily be determined thus providing a three-dimensionalmodel of the occupant or occupying object in the case of other vehicletypes such as a cargo container or truck trailer.

As a result, the current assignee has developed a low cost single camerasystem which has been extensively tested for the most difficult problemof automobile occupant sensing but is nevertheless also applicable formonitoring of other vehicles such as cargo containers and trucktrailers. The automotive occupant position sensor system uses a CMOScamera in conjunction with pattern recognition algorithms for thediscrimination of out-of-position occupants and rear facing child safetyseats. A single imager, located strategically within the occupantcompartment, is coupled with an infrared LED that emits unfocused,wide-beam pulses toward the passenger volume. These pulses, whichreflect off of objects in the passenger seat and are captured by thecamera, contain information for classification and locationdetermination in approximately 10 msec. The decision algorithm processesthe returned information using a uniquely trained neural network, whichmay not be necessary in the simpler cargo container or truck trailermonitoring cases. The logic of the neural network was developed throughextensive in-vehicle training with thousands of realistic occupant sizeand position scenarios. Although the optical occupant position sensorcan be used in conjunction with other technologies (such as weightsensing, seat belt sensing, crash severity sensing, etc.), it is astand-alone system meeting the requirements of FMVSS-208. This devicewill be discussed in detail below.

3.2 Location of the Transducers

Any of the transducers discussed herein such as an active pixel or othercamera can be arranged in various locations in the vehicle including ina headliner, roof, ceiling, rear view mirror assembly, an A-pillar, aB-pillar and a C-pillar or a side wall or even a door in the case of acargo container or truck trailer. Images of the front seat area or therear seat area can be obtained by proper placement and orientation ofthe transducers such as cameras. The rear view mirror assembly can be agood location for a camera, particularly if it is attached to theportion of the mirror support that does not move when the occupant isadjusting the mirror. Cameras at this location can get a good view ofthe driver, passenger as well as the environment surrounding the vehicleand particularly in the front of the vehicle. It is an ideal locationfor automatic dimming headlight cameras.

4. Weight Measurement and Biometrics

One way to determine motion of the occupant(s) is to monitor the weightdistribution of the occupant whereby changes in weight distributionafter an accident would be highly suggestive of movement of theoccupant. A system for determining the weight distribution of theoccupants can be integrated or otherwise arranged in the seats 3 and 4of the vehicle and several patents and publications describe suchsystems.

More generally, any sensor that determines the presence and health stateof an occupant can also be integrated into the vehicle interiormonitoring system in accordance with the inventions herein. For example,a sensitive motion sensor can determine whether an occupant is breathingand a chemical sensor, such as accomplished using SAW technology, candetermine the amount of carbon dioxide, or the concentration of carbondioxide, in the air in the vehicle, which can be correlated to thehealth state of the occupant(s). The motion sensor and chemical sensorcan be designed to have a fixed operational field situated near theoccupant. In the alternative, the motion sensor and chemical sensor canbe adjustable and adapted to adjust their operational field inconjunction with a determination by an occupant position and locationsensor that would determine the location of specific parts of theoccupant's body such as his or her chest or mouth. Furthermore, anoccupant position and location sensor can be used to determine thelocation of the occupant's eyes and determine whether the occupant isconscious, that is, whether his or her eyes are open or closed ormoving.

Chemical sensors can also be used to detect whether there is bloodpresent in the vehicle such as after an accident. Additionally,microphones can detect whether there is noise in the vehicle caused bygroaning, yelling, etc., and transmit any such noise through thecellular or similar connection to a remote listening facility using atelematics communication system such as operated by OnStar™.

FIG. 2A shows a schematic diagram of an embodiment of the inventionincluding a system for determining the presence and health state of anyoccupants of the vehicle and a telecommunications link. This embodimentincludes means 150 for determining the presence of any occupants 151,which may take the form of a heartbeat sensor, chemical sensor or motionsensor as described above and means for determining the health state ofany occupants 151. The latter means may be integrated into the means fordetermining the presence of any occupants using the same or differentcomponent. The presence determining means 150 may encompass a dedicatedpresence determination device associated with each seating location inthe vehicle, or at least sufficient presence determination deviceshaving the ability to determine the presence of an occupant at eachseating location in the vehicle. Further, means for determining thelocation, and optionally velocity, of the occupants or one or more partsthereof 152 are provided and may be any conventional occupant positionsensor or preferably, one of the occupant position sensors as describedherein such as those utilizing waves such as electromagnetic radiationor fields such as capacitance sensors or as described in the currentassignee's patents and patent applications referenced above as well asherein.

A processor 153 is coupled to the presence determining means 150, thehealth state determining means 151 and the location determining means152. A communications unit 154 is coupled to the processor 153. Theprocessor 153 and/or communications unit 154 can also be coupled tomicrophones 158 that can be distributed throughout the vehicle passengercompartment and include voice-processing circuitry to enable theoccupant(s) to effect vocal control of the processor 153, communicationsunit 154 or any coupled component or oral communications via thecommunications unit 154. The processor 153 is also coupled to anothervehicular system, component or subsystem 155 and can issue controlcommands to effect adjustment of the operating conditions of the system,component or subsystem. Such a system, component or subsystem can be theheating or air-conditioning system, the entertainment system, anoccupant restraint device such as an airbag, a glare prevention system,etc. Also, a positioning system 156, such as a GPS or differential GPSsystem, could be coupled to the processor 153 and provides an indicationof the absolute position of the vehicle.

Pressure or weight sensors 7, 76 and 97 are also included in the systemshown in FIGS. 6 and 6A. Although strain gage-type sensors areschematically illustrated mounted to the supporting structure of theseat portion 4, and a bladder pressure sensor mounted in the seatportion 4, any other type of pressure or weight sensor can be usedincluding mat or butt spring sensors. Strain gage sensors are describedin detail in U.S. Pat. No. 6,242,701 as well as herein. Weight can beused to confirm the occupancy of the seat, i.e., the presence or absenceof an occupant as well as whether the seat is occupied by a light orheavy object. In the latter case, a measured weight of less than 60pounds is often determinative of the presence of a child seat whereas ameasured weight of greater than 60 pounds is often indicative of theabsence of a child seat. The weight sensors 7 can also be used todetermine the weight distribution of the occupant of the seat andthereby ascertain whether the occupant is moving and the position of theoccupant. As such, the weight sensors 7 could be used to confirm theposition and motion of the occupant. The measured pressure or weight ordistribution thereof can also be used in combination with the data fromthe transmitter/receiver assemblies 49, 50, 51, 52 and 54 of FIG. 8C toprovide an identification of the occupants in the seat.

As discussed below, weight can be measured both statically anddynamically. Static weight measurements require that the pressure orstrain gage system be accurately calibrated and care must be taken tocompensate for the effects of seatbelt load, aging, unwanted stresses inthe mounting structures, temperature etc. Dynamic measurements, on theother hand, can be used to measure the mass of an object on the seat,the presence of a seatbelt load and can be made insensitive to unwantedstatic stresses in the supporting members and to aging of the seat andits structure. In the simplest implementation, the natural frequency ofseat is determined due to the random vibrations or accelerations thatare input to the seat from the vehicle suspension system. In moresophisticated embodiments, an accelerometer and/or seatbelt tensionsensor is also used to more accurately determine the forces acting onthe occupant. In another embodiment, a vibrator can be used inconjunction with the seat to excite the seat occupying item either on atotal basis or on a local basis using PVDF film as an exciter and adetermination of the contact pattern of the occupant with the seatdetermined by the local response to the PVDF film. This latter methodusing the PVDF film or equivalent is closer to a pattern determinationrather than a true weight measurement.

Although many weight sensing systems are described herein, at least oneof the inventions disclosed herein is, among other things, directed tothe use of weight in any manner to determine the occupancy of a vehicle.Prior art mat sensors determined the occupancy through the butt print ofthe occupying item rather than actually measuring its weight. In an evenmore general sense, at least one of the inventions disclosed herein isthe use of any biometric measurement to determine vehicle occupancy.

As to the latter issue, when an occupant or object is strapped into theseat using a seatbelt, it can cause an artificial load on a bladder-typeweight sensor and/or strain gage-type weight sensors when the seatbeltanchorage points are not on the seat. The effects of seatbelt load canbe separated from the effects of object or occupant weight, as disclosedin U.S. Pat. No. 6,242,701, if the time-varying signals are consideredrather than merely using averaging to obtain the static load. If avehicle-mounted vertical accelerometer is present, then the forcingfunction on the seat caused by road roughness, steering maneuvers, andthe vehicle suspension system can be compared with the response of theseat as measured by the bladder or strain gage pressure or weightsensors. Through mathematical analysis, the magnitude of the bladderpressure or strain caused by seat belt loads can be separated frompressure and strain caused by occupant or object mass. Also, sinceanimated objects such as people cannot sit still indefinitely, suchoccupants can be distinguished from inanimate objects by similarlyobserving the change in pressure and strain distribution over time.

A serious problem that has plagued researchers attempting to adaptstrain gage technology to seat weight sensing arises from fact that atypical automobile seat is an over-determined structure containingindeterminate stresses and strains in the supporting structure. Thisarises from a variety of causes such as the connection between the seatstructure and the slide mechanisms below the seat or between the slidemechanisms and the floor which induces twisting and bending moments inthe seat structural members. Similarly, since most seats have fourattachment points and since only three points are necessary to determinea plane, there can be an unexpected distribution of compression andtensile stresses in the support structure. To complicate the situation,these indeterminable stresses and strains can vary as a function of seatposition and temperature. The combination of all of these effectsproduces a significant error in the calculation of the weight of anoccupying item and the distribution of this weight.

This problem can be solved by looking at changes in pressure and strainreadings in addition to the absolute values. The dynamic response of anoccupied seat is a function of the mass of the occupying item. As thecar travels down the road, a forcing function is provided to the seatwhich can be measured by the vertical acceleration component and otheracceleration components. This provides a method of measuring theresponse of the seat as well as the forcing function and therebydetermining the mass of occupying item.

For example, when an occupant first enters the vehicle and sits on aseat, the change in pressure and/or strain measurements will provide anaccurate measurement of the occupant's weight. This accuracydeteriorates as soon as the occupant attaches a seatbelt and/or movesthe seat to a new position. Nevertheless, the change in occupancy of theseat is a significant event that can be easily detected and if thechange in pressure and strain measurements are used as the measurementof the occupant weight, then the weight can be accurately determined.Similarly, the sequence of events for attaching a child seat to avehicle is one that can be easily discerned since the seat is firstplaced into the vehicle and the seat belt cinched followed by placingthe child in the seat or, alternately, the child and seat are placed inthe vehicle followed by a cinching of the seatbelt. Either of theseevent sequences gives a high probability of the occupancy being a childin a child seat. This decision can be confirmed by dynamicalmeasurements as described above.

A control system for controlling a component of the vehicle based onoccupancy of the seat in accordance with the invention may comprise aplurality of strain gages, or bladder chambers, mounted in connectionwith the seat, each measuring strain or pressure of a respectivelocation caused by occupancy of the seat, and a processor coupled to thestrain or pressure gages and arranged to determine the weight of anoccupying item based on the strain or pressure measurements from thestrain or pressure gages over a period of time, i.e., dynamicmeasurements. The processor controls the vehicle component based atleast in part on the determined weight of the occupying item of theseat. The processor can also determine motion of the occupying item ofthe seat based on the strain or pressure measurements from the strain orpressure gages over the period of time. One or more accelerometers maybe mounted on the vehicle for measuring acceleration in which case, theprocessor may control the component based at least in part on thedetermined weight of the occupying item of the seat and the accelerationmeasured by the accelerometer(s). (See the discussion below in referenceto FIG. 17.)

By comparing the output of various sensors in the vehicle, it ispossible to determine activities that are affecting parts of the vehiclewhile not affecting other parts. For example, by monitoring the verticalaccelerations of various parts of the vehicle and comparing theseaccelerations with the output of strain gage load cells placed on theseat support structure, or bladder sensors, a characterization can bemade of the occupancy of the seat. Not only can the weight of an objectoccupying the seat be determined, but also the gross motion of such anobject can be ascertained and thereby an assessment can be made as towhether the object is a life form such as a human being and whether theseatbelt is engaged. Strain gage weight sensors are disclosed, forexample, in U.S. Pat. No. 6,242,701. In particular, the inventorcontemplates the combination of all of the ideas expressed in the '701patent with those expressed in the current invention.

Thus, the combination of the outputs from these accelerometer sensorsand the output of strain gage or bladder weight sensors in a vehicleseat, or in or on a support structure of the seat, can be used to makean accurate assessment of the occupancy of the seat and differentiatebetween animate and inanimate occupants as well as determining where inthe seat the occupants are sitting and whether the seatbelt is engaged.This can be done by observing the acceleration signals from the sensorsof FIG. 17 and simultaneously the dynamic strain gage measurements fromseat-mounted strain or pressure gages or pressure measurements ofbladder weight sensors. The accelerometers provide the input function tothe seat and the strain gages measure the reaction of the occupying itemto the vehicle acceleration and thereby provide a method of determiningdynamically the mass of the occupying item and its location. This isparticularly important during occupant position sensing during a crashevent. By combining the outputs of the accelerometers and the straingages and appropriately processing the same, the mass and weight of anobject occupying the seat can be determined as well as the gross motionof such an object so that an assessment can be made as to whether theobject is a life form such as a human being and whether a seatbelt isused and if so how tightly it is cinched.

Both strain gage and bladder weight sensors will be considered in detailbelow. There are of course several ways to process the accelerationsignal and the stain or pressure signal or any other weight measuringapparatus. In general, the dynamic load applied to the seat is measuredor a forcing function of the seat is measured, as a function of theacceleration signal. This represents the effect of the movement of thevehicle on the occupant which is reflected in the measurement of weightby the strain or pressure gages. Thus, the measurement obtained by thestrain or pressure gages can be considered to have two components, onecomponent resulting from the weight applied by the occupant in astationary state of the vehicle and the other arising or resulting fromthe movement of the vehicle. The vehicle-movement component can beseparated from the total strain or pressure gage measurement to providea more accurate indication of the weight of the occupant.

To provide a feeling for the implementation of at least one of theinventions disclosed herein, consider the following approximateanalysis.

To begin with, the seatbelt can be represented as a one-way spring inthat the force is high for upward motion and low for downward motion.This however introduces non-linearity into the analysis making an exactsolution difficult. Therefore for the purposes of this simplifiedanalysis, an assumption is made that the force from the seatbelt is thesame in both directions. Although the stiffness of the seat will varysignificantly from vehicle to vehicle, assume here that it is about 30kg per cm. Also assume that the input from the road is 1 Hz with amagnitude of 10 cm for the vertical motion of the vehicle wheels (axle)on the road. The motion of the seat will be much less due to the vehiclesuspension system.

The problem is to find is the weight of an occupant from the response ofthe seat (as measured by strain or pressure gages) to the roaddisplacement acting through the vehicle suspension. The intent here isonly to show that it is possible to determine the weight of the occupantand the use of a seatbelt by measuring the dynamic strain or pressuredue to the seat motion as a function of the weight of the occupant andthe seatbelt force. The functions and equations used below and thesolution to them can be implemented in a processor.

Looking now at FIG. 6B, suppose that point A (the point where a seatbeltis fixed to the seat) and point B are subjected to harmonicdisplacements u(t)=U₀cosωt caused by a car's vertical movements on theroad. As a result, springs modeling a seat and a seatbelt (theircorresponding stiffness are k_(s) and k_(sb)) affect a passenger mass mwith forces −k_(sb)(u−x) and k_(s)(u−x). (Minus in the first force istaken because the seatbelt spring contracts when the seat springstretches and vice versa). Under the action forces, the mass getsaccelerated d²x/dt², so the initial equation to be solved will be$\begin{matrix}{{m\frac{\mathbb{d}{\,^{2}x}}{\mathbb{d}t^{2}}} = {{- {k_{sb}\left( {u - x} \right)}} + {{k_{s}\left( {u - x} \right)}.}}} & (1)\end{matrix}$

This equation can be rewritten in the form $\begin{matrix}{{{m\frac{\mathbb{d}{\,^{2}x}}{\mathbb{d}t^{2}}} + {\left( {k_{s} - k_{sb}} \right)x}} = {{u(t)}{\left( {k_{s} - k_{sb}} \right).{or}}}} & (2) \\{{{m\frac{\mathbb{d}{\,^{2}x}}{\mathbb{d}t^{2}}} + {\left( {k_{s} - k_{sb}} \right)x}} = {{U_{0}\left( {k_{s} - k_{sb}} \right)}\cos\quad\omega\quad t}} & (3)\end{matrix}$

This is a differential equation of a harmonic oscillator under action ofa harmonic external force f(t)=U₀(t)(k_(s)−k_(sb))cosωt. If there is noseatbelt (k_(sb)=0), the solution of this equation in the case of aharmonic external force f(t)=F₀cosωt is well known [Strelkov S. P.Introduction in the theory of oscillations, Moscow, “Nauka”, 1964, p.56]: $\begin{matrix}{{{x(t)} = {{\frac{U_{0}}{\left( {1 - \frac{\omega^{2}}{\omega_{0}^{2}}} \right)}\cos\quad\omega\quad t} + {C_{1}\cos\quad\omega_{0}t} + {C_{2}\sin\quad\omega_{0}t}}},} & (4)\end{matrix}$

where the oscillator natural frequency. $\begin{matrix}{{\omega_{0} = {\sqrt{\frac{k_{s}}{m}}.}}\quad} & (5)\end{matrix}$

The second and third terms in equation (4) describe natural oscillationsof the oscillator, which decay if there is any, even very small,friction in the system. Having assumed such small friction to bepresent, for steady forced oscillation, the equation is thus:$\begin{matrix}{{x(t)} = {\frac{U_{0}}{1 - \frac{\omega^{2}}{\omega_{0}^{2}}}\cos\quad\omega\quad{t.}}} & (6)\end{matrix}$

Thus, in steady mode the system oscillates with the external forcefrequency ω. Now, it is possible to calculate acceleration of the mass:$\begin{matrix}{{\frac{\mathbb{d}{\,^{2}x}}{\mathbb{d}t^{2}} = {{- \frac{\omega^{2}U_{0}}{1 - \frac{\omega^{2}}{\omega_{0}^{2}}}}\cos\quad\omega\quad t}},} & (7)\end{matrix}$

and the amplitude of the force acting in the system $\begin{matrix}{F_{m} = {{{m\frac{\mathbb{d}{\,^{2}x}}{\mathbb{d}t^{2}}}} = {{{- \frac{m\quad\omega^{2}U_{0}}{1 - \frac{\omega^{2}}{\omega_{0}^{2}}}}}.}}} & (8)\end{matrix}$

In the situation where a seatbelt is present, it is not possible to usethe same formulae because the seatbelt stiffness is always greater thanstiffness of a seat, and (k_(s)−k_(sb))<0. Therefore, instead ofequation (3) we should consider the equation $\begin{matrix}{{{\frac{\mathbb{d}{\,^{2}x}}{\mathbb{d}t^{2}} - {\omega_{0}^{2}x}} = {{- \omega_{0}^{2}}U_{0}\cos\quad\omega\quad t}},} & (9)\end{matrix}$where ω₀ ²=|k_(s)−k_(sb)|/m>0. Following the same procedure (Strelkov S.P., ibid.), one can find a particular solution of inhomogeneous equation(9): $\begin{matrix}{{x(t)} = {\frac{U_{0}}{1 + \frac{\omega^{2}}{\omega_{0}^{2}}}\cos\quad\omega\quad{t.}}} & (10)\end{matrix}$

Then its general solution will be [as per Korn G. A., Korn T. M.Mathematical handbook for scientists and engineers. Russian translation:Moscow, “Nauka”, 1970, pp. 268-270]: $\begin{matrix}{{x(t)} = {{\frac{U_{0}}{\left( {1 + \frac{\omega^{2}}{\omega_{0}^{2}}} \right)}\cos\quad\omega\quad t} + {C_{1}\cos\quad\omega_{0}t} + {C_{2}\sin\quad\omega_{0}{t.}}}} & (11)\end{matrix}$

Thus, in a steady mode, the amplitude of the acting force is:$\begin{matrix}{{F_{m} = {{- \frac{m\quad\omega^{2}U_{0}}{1 + \frac{\omega^{2}}{\omega_{0}^{2}}}}}},} & (12)\end{matrix}$

and the natural frequency of the system is: $\begin{matrix}{\omega_{0} = {\sqrt{\frac{{k_{s} - k_{sb}}}{m}}.}} & (13)\end{matrix}$

Using the formulae (5), (8) (the “no seatbelt case”), (12) and (13) (the“seatbelt present case”), a table can be created as shown below. In thetable, p_(m) denotes amplitude of pressure acting on the seat surface.The initial data used in calculations are as follows:

-   -   k_(s)=30 Kg/cm=3×10⁴ N/m (the seat stiffness);    -   k_(sb)=600 N/0.3 cm=2×10⁵ N/m (the seatbelt stiffness);    -   U₀=0.1 m (the acting displacement amplitude);    -   f=1 Hz (the acting frequency).    -   S=0.05 m² (the seat surface square that the passenger acting        upon).

Naturally, where the frequency fω/2π, f₀ is natural frequency of thesystem. Columns “No seatbelt” is calculated when k_(sb)=0. The passengerNo seatbelt There is a seatbelt mass, kg f₀, Hz F_(m), N p_(m), Pa f₀,Hz F_(m), N p_(m), Pa 20 6.2 81.1 1.62 × 10³ 14.7 78.6 1.57 × 10³ 40 4.4166.7 3.33 × 10³ 10.4 156.5 3.13 × 10³ 60 3.6 257.2 5.14 × 10³ 8.5 233.64.67 × 10³ 100 2.8 454.6 9.09 × 10³ 6.6 385.8 7.72 × 10³

From the above table, it can be seen that there is a differentcombination of seat structure force (as can be measured by straingages), or pressure (as can be measured by a bladder and pressuresensor) and natural frequency for each combination of occupant weightand seatbelt use. Indeed, it can easily be seen that use of a seatbeltsignificantly affects the weight measurement of the weight sensors. Byusing the acceleration data, e.g., a forcing function, it is possible toeliminate the effect of the seatbelt and the road on the weightmeasurement. Thus, by observing the response of the seat plus occupantand knowing the input from the road, an estimate of the occupant weightand seatbelt use can be made without even knowing the static forces orpressures in the strain or pressure gages. By considering the dynamicresponse of the seat to road-induced input vibrations, the occupantweight and seatbelt use can be determined.

In an actual implementation, the above problem can be solved moreaccurately by using a pattern recognition system that compares thepattern of the seat plus occupant response (pressure or strain gagereadings) to the pattern of input accelerations. This can be donethrough the training of a neural network, modular neural network orother trainable pattern recognition system. Many other mathematicaltechniques can be used to solve this problem including varioussimulation methods where the coefficients of dynamical equations areestimated from the response of the seat and occupant to the inputacceleration. Thus, although the preferred implementation of the presentinvention is to use neural networks to solve this problem, the inventionis not limited thereby.

4.1 Strain Gage Weight Sensors

Referring now to FIG. 18A, which is a view of the apparatus of FIG. 18taken along line 18A-18A, seat 160 is constructed from a cushion or foamlayer 161 which is supported by a spring system 162 which is in contactand/or association with the displacement sensor 163. As shown,displacement sensor 163 is underneath the spring system 162 but thisrelative positioning is not a required feature of the invention. Thedisplacement sensor 163 comprises an elongate cable 164 retained at oneend by support 165 and a displacement sensor 166 situated at an oppositeend. This displacement sensor 166 can be any of a variety of suchdevices including, but not limited to, a linear rheostat, a linearvariable differential transformer (LVDT), a linear variable capacitor,or any other length measuring device. Alternately, as shown in FIG. 18C,the cable can be replaced with one or more springs 167 retained betweensupports 165 and the tension in the spring(s) 167 measured using astrain gage (conventional wire, foil, silicon or a SAW strain gage) orother force measuring device 168 or the strain in the seat supportstructure can be measured by appropriately placing strain gages on oneor more of the seat supports as described in more detail below. Thestrain gage or other force measuring device could be arranged inassociation with the spring system 162 and could measure the deflectionof the bottom surface of the cushion or foam layer 161.

When a SAW strain gage 168 is used as part of weight sensor 163, aninterrogator 169 could be placed on the vehicle to enable wirelesscommunication and/or power transfer to the SAW strain gage 168. As such,when it is desired to obtain the force being applied by the occupyingitem on the seat, the interrogator 169 sends a radio signal to the SAWstrain gage causing it to transmit a return signal with the measuredstrain of the spring 170. Interrogator 169 is coupled to the processorused to determine the control of the vehicle component.

As shown in FIG. 18D, one or more SAW strain gages 171 could also beplaced on the bottom surface or support pan 178 of the cushion or foamlayer 161 in order to measure the deflection of the bottom surface whichis representative of the weight of the occupying item on the seat or thepressure applied by the occupying item to the seat. An interrogator 169could also be used in this embodiment.

One seat design is illustrated in FIG. 18. Similar weight measurementsystems can be designed for other seat designs. Also, some products areavailable which can approximately measure weight based on pressuremeasurements made at or near the upper seat surface 172. It should benoted that the weight measured here will not be the entire weight of theoccupant since some of the occupant's weight will be supported by his orher feet which are resting on the floor or pedals. As noted above, theweight may also be measured by the weight sensor(s) 7, 76 and 97described above in the seated-state detecting unit.

As weight is placed on (pressure applied to) the seat surface 172, it issupported by spring system 162 which deflects downward causing cable 164of the sensor 163 to begin to stretch axially. Using a LVDT as anexample of length measuring device 166, the cable 164 pulls on rod 173tending to remove rod 173 from cylinder 174 (FIG. 18B). The movement ofrod 173 out of cylinder 174 is resisted by a spring 175 which returnsthe rod 173 into the cylinder 174 when the weight is removed from theseat surface 172. The amount which the rod 173 is removed from thecylinder 174 is measured by the amount of coupling between the windings176 and 177 of the transformer as is well understood by those skilled inthe art. LVDT's are commercially available devices. In this matter, thedeflection of the seat can be measured which is a measurement of theweight on the seat, i.e., the pressure applied by an occupying item tothe seat surface. The exact relationship between weight and LVDT outputis generally determined experimentally for this application.

SAW strain gages could also be used to determine the downward deflectionof the spring system 162 and the deflection of the cable 164.

By use of a combination of weight and height, the driver of the vehiclecan in general be positively identified among the class of drivers whooperate the vehicle. Thus, when a particular driver first uses thevehicle, the seat will be automatically adjusted to the proper position.If the driver changes that position within a prescribed time period, thenew seat position can be stored in the second table for the particulardriver's height and weight. When the driver reenters the vehicle and hisor her height and weight are again measured, the seat will go to thelocation specified in the second table if one exists. Otherwise, thelocation specified in the first table will be used. Naturally othermethods having similar end results can be used.

In a first embodiment of a weight measuring apparatus shown in FIG. 19,four strain gage weight sensors or transducers are used, two beingillustrated at 180 and 181 on one side of a bracket of the supportstructure of the seat and the other two being at the same locations onanother bracket of the support (i.e., hidden on the correspondinglocations on the other side of the support). The support structure ofthe seat supports the seat on a substrate such as a floor pan of thevehicle. Each of the strain gage transducers 180,181 also can containelectronic signal conditioning apparatus, e.g., amplifiers, analog todigital converters, filters etc., which is associated such that outputfrom the transducers is a digital signal. Such signal conditioningapparatus can also eliminate residual stresses in the transducerreadings that may be present from the manufacturing, assembly ormounting processes or due to seat motion or temperature. The electronicsignal travels from transducer 180 to transducer 181 through a wire 184.Similarly, wire 185 transmits the output from transducers 180 and 181 tothe next transducer in the sequence (one of the hidden transducers).Additionally, wire 186 carries the output from these three transducerstoward the fourth transducer (the other hidden transducer) and wire 187finally carries all four digital signals to an electronic control systemor module 188. These signals from the transducers 180, 181 are time,code or frequency division multiplexed as is well known in the art. Theseat position is controlled by motors 189 as described in detail in U.S.Pat. No. 5,179,576. Finally, the seat is bolted onto the supportstructure through bolts not shown which attach the seat through holes190 in the brackets.

By placing the signal conditioning electronics, analog to digitalconverters, and other appropriate electronic circuitry adjacent thestrain gage element, the four transducers can be daisy chained orotherwise attach together and only a single wire is required to connectall of the transducers to the control module 188 as well as provide thepower to run the transducers and their associated electronics.

The control system 188, e.g., a microprocessor, is arranged to receivethe digital signals from the transducers 180,181 and determine theweight of the occupying item of the seat based thereon. In other words,the signals from the transducers 180,181 are processed by the controlsystem 188 to provide an indication of the weight of the occupying itemof the seat, i.e., the pressure or force exerted by the occupying itemon the seat support structure.

A typical manually controlled seat structure is illustrated in FIG. 20and described in greater detail in U.S. Pat. No. 4,285,545. The seat 191(only the frame of which is shown) is attached to a pair of slidemechanisms 192 in the rear thereof through support members such asrectangular tubular structures 193 angled between the seat 191 and theslide mechanisms 192. The front of the seat 191 is attached to thevehicle (more particularly to the floor pan) through another supportmember such as a slide member 194, which is engaged with a housing 195.Slide mechanisms 192, support members 193, slide member 194 and housing195 constitute the support structure for mounting the seat on asubstrate, i.e., the floor pan. Strain gage transducers are located forthis implementation at 180 and 182, strain gage transducer 180 beingmounted on each tubular structure 193 (only one of such strain gage isshown) and strain gage transducer 182 being mounted on slide member 194.

When an occupying item is situated on the seat cushion (not shown), eachof the support members 193 and 194 are deformed or strained. This strainis measured by transducers 180 and 182, respectively, to enable adetermination of the weight of the item occupying the seat, as can beunderstood by those skilled in the strain gage art. More specifically, acontrol system or module or other compatible processing unit (not shown)is coupled to the strain gage transducers 180, 182, e.g., via electricalwires (not shown), to receive the measured strain and utilize themeasured strain to determine the weight of the occupying item of theseat or the pressure applied by the occupying item to the seat. Thedetermined weight, or the raw measured strain, may be used to control avehicular component such as the airbag.

Support members 193 are substantially vertically oriented and arepreferably made of a sufficiently rigid, non-bending component.

FIG. 20A illustrates an alternate arrangement for the seat supportstructures wherein a gusset 196 has been added to bridge the angle onthe support member 193. Strain gage transducer 180 is placed on thisgusset 196. Since the gusset 196 is not a supporting member, it can bemade considerably thinner than the seat support member 193. As the seatis loaded by an occupying item, the seat support member 193 will bend.Since the gusset 196 is relatively weak, greater strain will occur inthe gusset 196 than in the support member 193. The existence of thisgreater strain permits more efficient use of the strain gage dynamicrange thus improving the accuracy of the weight measurement.

FIG. 20B illustrates a seat transverse support member 197 of the seatshown in FIG. 20, which is situated below the base cushion and extendsbetween opposed lateral sides of the seat. This support member 197 willbe directly loaded by the vehicle seat and thus will provide an averagemeasurement of the force exerted or weight of the occupying item. Thedeflection or strain in support member 197 is measured by a strain gagetransducer 180 mounted on the support member 197 for this purpose. Insome applications, the support member 197 will occupy the entire spacefore and aft below the seat cushion. Here it is shown as a relativelynarrow member. The strain gage transducer 180 is coupled, e.g., via anelectrical wire (not shown), to a control module or other processingunit (not shown) which utilizes the measured strain to determine theweight of the occupying item of the seat.

In FIG. 20, the support members 193 are shown as rectangular tubeshaving an end connected to the seat 191 and an opposite end connected tothe slide mechanisms 192. In the constructions shown in FIGS. 21A-21C,the rectangular tubular structure has been replaced by a circular tubewhere only the lower portion of the support is illustrated. FIGS.21A-21C show three alternate ways of improving the accuracy of thestrain gage system, i.e., the accuracy of the measurements of strain bythe strain gage transducers. Generally, a reduction in the stiffness ofthe support member to which the strain gage transducer is mounted willconcentrate the force and thereby improve the strain measurement. Thereare several means disclosed below to reduce the stiffness of the supportmember. These means are not exclusive and other ways to reduce thestiffness of the support member are included in the invention and theinterpretation of the claims.

In each illustrated embodiment, the transducer is represented by 180 andthe substantially vertically oriented support member corresponding tosupport member 193 in FIG. 20 has been labeled 193A. In FIG. 21A, thetube support member 193A has been cut to thereby form two separate tubeshaving longitudinally opposed ends and an additional tube section 198 isconnected, e.g., by welding, to end portions of the two tubes. In thismanner, a more accurate tube section 198 can be used to permit a moreaccurate measurement of the strain by transducer 180, which is mountedon tube section 198.

In FIG. 21B, a small circumferential cut has been made in tube supportmember 193A so that a region having a smaller circumference than aremaining portion of the tube support member 193A is formed. This cut isused to control the diameter of the tube support member 193A at thelocation where strain gage transducer 180 is measuring the strain. Inother words, the strain gage transducer 180 is placed at a portionwherein the diameter thereof is less than the diameter of remainingportions of the tube support member 193A. The purpose of this cut is tocorrect for manufacturing variations in the diameter of the tube supportmember 193A. The magnitude of the cut is selected so as to notsignificantly weaken the structural member but instead to control thediameter tolerance on the tube so that the strain from one vehicle toanother will be the same for a particular loading of the seat.

In FIG. 21C, a small hole 200 is made in the tube support member 193Aadjacent the transducer 180 to compensate for manufacturing toleranceson the tube support member 193A.

From this discussion, it can be seen that all three techniques have astheir primary purpose to increase the accuracy of the strain in thesupport member corresponding to weight on the vehicle seat. Thepreferred approach would be to control the manufacturing tolerances onthe support structure tubing so that the variation from vehicle tovehicle is minimized. For some applications where accurate measurementsof weight are desired, the seat structure will be designed to optimizethe ability to measure the strain in the support members and thereby tooptimize the measurement of the weight of the occupying item. Theinventions disclosed herein, therefore, are intended to cover the entireseat when the design of the seat is such as to be optimized for thepurpose of strain gage weight sensing and alternately for the seatstructure when it is so optimized.

Although strain measurement devices have been discussed above, pressuremeasurement systems can also be used in the seat support structure tomeasure the weight on the seat. Such a system is illustrated in FIG. 22.A general description of the operation of this apparatus is disclosed inU.S. Pat. No. 5,785,291. In that patent, the vehicle seat is attached tothe slide mechanism by means of bolts 201. Between the seat and theslide mechanism, a shock-absorbing washer has been used for each bolt.In the present invention, this shock-absorbing washer has been replacedby a sandwich construction consisting of two washers of shock absorbingmaterial 202 with a pressure sensitive material 203 sandwiched inbetween.

A variety of materials can be used for the pressure sensitive material203, which generally work on either the capacitance or resistive changeof the material as it is compressed. The wires from this material 203leading to the electronic control system are not shown in this view. Thepressure sensitive material 203 is coupled to the control system, e.g.,a microprocessor, and provides the control system with an indication ofthe pressure applied by the seat on the slide mechanism which is relatedto the weight of the occupying item of the seat. Generally, material 203is constructed with electrodes on the opposing faces such that as thematerial 202 is compressed, the spacing between the electrodes isdecreased. This spacing change thereby changes both the resistive andthe capacitance of the sandwich which can be measured and which is afunction of the compressive force on the material 202. Measurement ofthe change in capacitance of the sandwich, i.e., two spaced apartconductive members, is obtained by any method known to those skilled inthe art, e.g., connecting the electrodes in a circuit with a source ofalternating or direct current. The conductive members may be made of ametal. The use of such a pressure sensor is not limited to theillustrated embodiment wherein the shock absorbing material 202 andpressure sensitive material 203 are placed around bolt 201. It is alsonot limited to the use or incorporation of shock absorbing material inthe implementation.

FIG. 22A shows a substitute construction for the bolt 201 in FIG. 22 andwhich construction is preferably arranged in connection with the seatand the adjustment slide mechanism. A bolt-like member, hereinafterreferred to as a stud 204, is threaded 205 on both ends with a portionremaining unthreaded between the ends. A SAW strain measuring deviceincluding a SAW strain gage 206 and antenna 207 is arranged on thecenter unthreaded section of the stud 400 and the stud 400 is attachedat its ends to the seat and the slide mechanism using appropriatethreaded nuts. Based on the particular geometry of the SAW device used,the stud 400 can result in as little as a 3 mm upward displacement ofthe seat compared to a normal bolt mounting system. No wires arerequired to attach the SAW device to the stud 204. The total length ofstud 204 may be as little as 1 inch. Antennas larger than one inch maybe required depending on the frequency and antenna technology used andother considerations.

In operation, an interrogator 208 transmits a radio frequency pulse atfor example, 925 MHz, which excites the antenna 207 associated with theSAW strain gage 206. After a delay caused by the time required for thewave to travel the length of the SAW device, a modified wave isre-transmitted to the interrogator 208 providing an indication of thestrain and thus a representative value of the weight of an objectoccupying the seat. For a seat which is normally bolted to the slidemechanism with four bolts, at least four SAW strain measuring devices orsensors would be used. Each conventional bolt could thus be replaced bya stud as described above. Since the individual SAW devices are verysmall, multiple such SAW devices can be placed on the stud to providemultiple redundant measurements or to permit the stud to be arbitrarilylocated with at least one SAW device always within direct view of theinterrogator antenna. Note that if quarter wave dipole antennas areused, they may be larger than the strain gage and may in that case needto be mounted to the seat bottom, for example, or some other convenientplace. This, however, will also make it easier to align the antennaswith the interrogator antenna.

To avoid potential problems with electromagnetic interference, the stud204 may be made of a non-metallic, possibly composite, material whichwould not likely cause or contribute to any possible electromagneticwave interference. The stud 204 could also be modified for use as anantenna.

If the seat is unoccupied, then the interrogation frequency can besubstantially reduced in comparison to when the seat is occupied. For anoccupied seat, information as to the identity and/or category andposition of an occupying item of the seat can be obtained through theuse of multiple weight sensors. For this reason, and due to the factthat during pre-crash event the position of an occupying item of theseat may be changing rapidly, interrogations as frequently as once every10 milliseconds or even faster can be desirable. This would also enablea distribution of the weight being applied to the seat being obtainedwhich provides an estimation of the position of the object occupying theseat. Using pattern recognition technology, e.g., a trained neuralnetwork, sensor fusion, fuzzy logic, etc., the identification of theobject can be ascertained based on the determined weight and/ordetermined weight distribution.

Although each of the SAW devices can be interrogated and/or poweredusing wireless means, in some cases, it may be desirable to supply powerto and or obtained information from such devices using wires. Also,strain gage coupled to circuits employing RFID type technology (noon-board power) can also result in a wireless interrogation system.Additionally, energy harvesting techniques can be used to generate thepower required. Conventional strain gages can also be used.

In FIG. 23, which is a view of a seat attachment structure described inU.S. Pat. No. 5,531,503, a more conventional strain gage load celldesign designated 209 is utilized. One such load cell design 209 isillustrated in detail in FIG. 23A.

A cantilevered beam load cell design using a half bridge strain gagesystem 209 is shown in FIG. 23A. Fixed resistors mounted within theelectronic package, which are not shown in this drawing, provide theremainder of the whetstone bridge system. The half bridge system isfrequently used for economic reasons and where some sacrifice inaccuracy is permissible. The load cell 209 includes a member 211 onwhich the strain gage 210 is situated. The strain gage assembly 209includes strain-measuring elements 212 and 213 arranged on the loadcell. The longitudinal element 212 measures the tensile strain in thebeam when it is loaded by the seat and its contents, not shown, which isattached to end 215 of bolt 214. The load cell is mounted to the vehicleor other substrate using bolt 217. Temperature compensation is achievedin this system since the resistance change in strain elements 212 and213 will vary the same amount with temperature and thus the voltageacross the portions of the half bridge will remain the same. The straingage 209 is coupled to a control system (e.g., a microprocessor—notshown) via wires 216 and receives the measured tensile strain anddetermines the weight of an occupying item of the seat based thereon.

One problem with using a cantilevered load cell is that it imparts atorque to the member on which it is mounted. One preferred mountingmember on an automobile is the floor-pan which will support significantvertical loads but is poor at resisting torques since floor-pans aretypically about 1 mm (0.04 inches) thick. This problem can be overcomethrough the use of a simply supported load cell design designated 220 asshown in FIG. 23B.

In FIGS. 23B and 23C, a full bridge strain gage system 221 is used withall four elements 222, 223 mounted on the top of a beam 240. Elements222 are mounted parallel to the beam 240 and elements 223 are mountedperpendicular to it. Since the maximum strain is in the middle of thebeam 240, strain gage 221 is mounted close to that location. The loadcell, shown generally as 220, is supported by the floor pan, not shown,at supports 234 that are formed by bending the beam 240 downward at itsends. Fasteners 228 fit through holes 229 in the beam 240 and serve tohold the load cell 220 to the floor pan without putting significantforces on the load cell 220. Holes are provided in the floor-pan for abolt 231 and for fasteners 228. Bolt 231 is attached to the load cell220 through hole 230 of the beam 240 which serves to transfer the forcefrom the seat to the load cell 220 Although this design would place theload cell 220 between the slide mechanism and the floor, in manyapplications it would be placed between the seat and the slidemechanism. In the first case, the evaluation algorithm may also requirea seat position input if the weight distribution is to be determined.

The electronics package can be potted within hole 235 using urethanepotting compound 232 and can include signal conditioning circuits, amicroprocessor with integral ADCs 226 and a flex circuit 225 (FIG. 23C).The flex circuit 225 terminates at an electrical connector 233 forconnection to other vehicle electronics, e.g., a control system. Thebeam 240 is slightly tapered at location 227 so that the strain isconstant in the strain gage.

Although thus far only beam-type load cells have been described, othergeometries can also be used. One such geometry is a tubular type loadcell. Such a tubular load cell is shown generally at 241 in FIG. 23D andinstead of an elongate beam, it includes a tube. It also comprises aplurality of strain sensing elements 242 for measuring tensile andcompressive strains in the tube as well as other elements, not shown,which are placed perpendicular to the elements 242 to provide fortemperature compensation. Temperature compensation is achieved in thismanner, as is well known to those skilled in the art of the use ofstrain gages in conjunction with a whetstone bridge circuit, sincetemperature changes will affect each of the strain gage elementsidentically and the total effect thus cancels out in the circuit. Thesame bolt 243 can be used in this case for mounting the load cell to thefloor-pan and for attaching the seat to the load cell.

Another alternate load cell design shown generally in FIG. 23E as 242makes use of a torsion bar 243 and appropriately placed torsional strainsensing elements 244. A torque is imparted to the bar 243 by means oflever 245 and bolt 246 which attaches to the seat structure not shown.Bolts 247 attach the mounting blocks 248 at ends of the torsion bar 243to the vehicle floor-pan.

The load cells illustrated above are all preferably of the foil straingage-type. Other types of strain gages exist which would work equallywell which include wire strain gages and strain gages made from silicon.Silicon strain gages have the advantage of having a much larger gagefactor and the disadvantage of greater temperature effects. For thehigh-volume implementation of at least one of the inventions disclosedherein, silicon strain gages have an advantage in that the electroniccircuitry (signal conditioning, ADCs, etc.) can be integrated with thestrain gage for a low cost package.

Other strain gage materials and load cell designs may, of course, beincorporated within the teachings of at least one of the inventionsdisclosed herein. In particular, a surface acoustical wave (SAW) straingage can be used in place of conventional wire, foil or silicon straingages and the strain measured either wirelessly or by a wire connection.For SAW strain gages, the electronic signal conditioning can beassociated directly with the gage or remotely in an electronic controlmodule as desired. For SAW strain gages, the problems discussed abovewith low signal levels requiring bridge structures and the methods fortemperature compensation may not apply. Generally, SAW strain gages aremore accurate that other technologies but may require a separate sensorto measure the temperature for temperature compensation depending on thematerial used. Materials that can be considered for SAW strain gages arequartz, lithium niobate, lead zirconate, lead titanate, zinc oxide,polyvinylidene fluoride and other piezoelectric materials.

Many seat designs have four attachment points for the seat structure toattach to the vehicle. Since the plane of attachment is determined bythree points, the potential exists for a significant uncertainty orerror to be introduced. This problem can be compounded by the method ofattachment of the seat to the vehicle. Some attachment methods usingbolts, for example, can introduce significant strain in the seatsupporting structure. Some compliance therefore should be introducedinto the seat structure to reduce these attachment-induced stresses to aminimum. Too much compliance, on the other hand, can significantlyweaken the seat structure and thereby potentially cause a safety issue.This problem can be solved by rendering the compliance section of theseat structure highly nonlinear or significantly limiting the range ofthe compliance. One of the support members, for example, can be attachedto the top of the seat structure through the use of the pinned jointwherein the angular rotation of the joint is severely limited. Methodswill now be obvious to those skilled in the art to eliminate theattachment-induced stress and strain in the structure which can causeinaccuracies in the strain measuring system.

In the examples illustrated above, strain measuring elements have beenshown at each of the support members. This of course is necessary if anaccurate measurement of the weight of the occupying item of the seat isto be determined. For this case, typically a single value is inputtedinto the neural network representing weight. Experiments have shown,however, for the four strain gage transducer system, that most of theweight and thus most of the strain occurs in the strain elements mountedon the rear seat support structural members. In fact, about 85 percentof the load is typically carried by the rear supports. Little accuracyis lost therefore if the forward strain measuring elements areeliminated. Similarly, for most cases, the two rear-mounted supportstrain elements measure approximately the same strain. Thus, theinformation represented by the strain in one rear seat support issufficient to provide a reasonably accurate measurement of the weight ofthe occupying item of the seat. Thus, at least one of the inventionsdisclosed herein can be implemented using one or more load cells orstrain gages. As disclosed elsewhere herein, other sensors, such asoccupant position sensors based on spatial monitoring technologies, canbe used in conjunction with one or more load cells or other pressure orweight sensors to augment and improve the accuracy of the system. Asimple position sensor mounted in the seat back or headrest, forexample, as illustrated at 354-365 in FIGS. 18, 24 and 25 can be used.

If a system consisting of eight transducers is considered, fourultrasonic transducers and four weight transducers, and if costconsiderations require the choice of a smaller total number oftransducers, it is a question of which of the eight transducers shouldbe eliminated. Fortunately, the neural network technology provides atechnique for determining which of the eight transducers is mostimportant, which is next most important, etc. If the six most criticaltransducers are chosen, that is the six transducers which contain themost useful information as determined by the neural network, a neuralnetwork can be trained using data from those six transducers and theoverall accuracy of the system can be determined. Experience hasdetermined, for example, that typically there is almost no loss inaccuracy by eliminating two of the eight transducers, that is two of thestrain gage weight sensors. A slight loss of accuracy occurs when one ofthe ultrasonic transducers is then eliminated.

This same technique can be used with the additional transducersdescribed above. A transducer space can be determined with perhapstwenty different transducers comprised of ultrasonic, optical,electromagnetic, motion, heartbeat, weight, seat track, seatbelt payout,seatback angle etc. transducers. The neural network can then be used inconjunction with a cost function to determine the cost of systemaccuracy. In this manner, the optimum combination of any system cost andaccuracy level can be determined.

In many situations where the four strain measuring weight sensors areapplied to the vehicle seat structure, the distribution of the weightamong the four strain gage sensors, for example, will vary significantlydepending on the position of the seat in the vehicle, and particularlythe fore and aft location, and secondarily, the seatback angle position.A significant improvement to the accuracy of the strain gage weightsensors, particularly if less than four such sensors are used, canresult by using information from a seat track position and/or a seatbackangle sensor. In many vehicles, such sensors already exist and thereforethe incorporation of this information results in little additional costto the system and results in significant improvements in the accuracy ofthe weight sensors.

There have been attempts to use seat weight sensors to determine theload distribution of the occupying item and thereby reach a conclusionabout the state of seat occupancy. For example, if a forward facinghuman is out of position, the weight distribution on the seat will bedifferent than if the occupant is in position. Similarly, a rear facingchild seat will have a different weight distribution than a forwardfacing child seat. This information is useful for determining the seatedstate of the occupying item under static or slowly changing conditions.For example, even when the vehicle is traveling on moderately roughroads, a long term averaging or filtering technique can be used todetermine the total weight and weight distribution of the occupyingitem. Thus, this information can be useful in differentiating between aforward facing and rear facing child seat.

It is much less useful however for the case of a forward facing human orforward facing child seat that becomes out of position during a crash.Panic braking prior to a crash, particularly on a rough road surface,will cause dramatic fluctuations in the output of the strain sensingelements. Filtering algorithms, which require a significant time sliceof data, will also not be particularly useful. A neural network or otherpattern recognition system, however, can be trained to recognize suchsituations and provide useful information to improve system accuracy.

Other dynamical techniques can also provide useful informationespecially if combined with data from the vehicle crash accelerometer.By studying the average weight over a few cycles, as measured by eachtransducer independently, a determination can be made that the weightdistribution is changing. Depending on the magnitude of the change, adetermination can be made as to whether the occupant is being restrainedby a seatbelt. If a seatbelt restraint is not being used, the outputfrom the crash accelerometer can be used to accurately project theposition of the occupant during pre-crash braking and eventually theimpact itself providing his or her initial position is known.

In this manner, a weight sensor with provides weight distributioninformation can provide useful information to improve the accuracy ofthe occupant position sensing system for dynamic out of positiondetermination. Even without the weight sensor information, the use ofthe vehicle crash sensor data in conjunction with any means ofdetermining the belted state of the occupant will dramatically improvethe dynamic determination of the position of a vehicle occupant. The useof the dynamics of the occupant to measure weight dynamically isdisclosed in the current assignee's U.S. patent application Ser. No.10/174,803 filed Jun. 19, 2002.

Strain gage weight sensors can also be mounted in other locations suchas within a cavity within a seat cushion as shown as 97 in FIG. 6A anddescribed above. The strain gage can be mounted on a flexible diaphragmthat flexes and thereby strains the strain gage as the seat is loaded.In the example of FIG. 6A, a single chamber 98, diaphragm and straingage 97 is illustrated. A plurality of such chambers can be used toprovide a distribution of the load on the occupying item onto the seat.

There are several applications for weight or load measuring devices in avehicle including the vehicle suspension system and seat weight sensorsfor use with automobile safety systems. As reported in U.S. Pat. No.4,096,740, U.S. Pat. No. 4,623,813, U.S. Pat. No. 5,585,571, U.S. Pat.No. 5,663,531, U.S. Pat. No. 5,821,425 and U.S. Pat. No. 5,910,647 andInternational Publication No. WO 00/65320(A1), SAW devices areappropriate candidates for such weight measurement systems. In thiscase, the surface acoustic wave on the lithium niobate, or otherpiezoelectric material, is modified in delay time, resonant frequency,amplitude and/or phase based on strain of the member upon which the SAWdevice is mounted. For example, the conventional bolt that is typicallyused to connect the passenger seat to the seat adjustment slidemechanism can be replaced with a stud which is threaded on both ends. ASAW strain device is mounted to the center unthreaded section of thestud and the stud is attached to both the seat and the slide mechanismusing appropriate threaded nuts. Based on the particular geometry of theSAW device used, the stud can result in as little as a 3 mm upwarddisplacement of the seat compared to a normal bolt mounting system. Nowires are required to attach the SAW device to the stud. Theinterrogator transmits a radio frequency pulse at, for example, 925 MHz,that excites antenna on the SAW strain measuring system. After a delaycaused by the time required for the wave to travel the length of the SAWdevice, a modified wave is re-transmitted to the interrogator providingan indication of the strain of the stud with the weight of an objectoccupying the seat corresponding to the strain. For a seat that isnormally bolted to the slide mechanism with four bolts, at least fourSAW strain sensors would be used. Since the individual SAW devices canbe small, multiple devices can be placed on a stud to provide multipleredundant measurements, or permit bending strains to be determined,and/or to permit the stud to be arbitrarily located with at least oneSAW device always within direct view of the interrogator antenna. Insome cases, the bolt or stud will be made on non-conductive material tolimit the blockage of the RF signal. In other cases, it will beinsulated from the slide (mechanism) and used as an antenna.

If two longitudinally spaced apart antennas are used to receive the SAWtransmissions from the seat weight sensors, one antenna in front of theseat and the other behind the seat, then the position of the seat can bedetermined eliminating the need for current seat position sensors. Asimilar system can be used for other seat and seatback positionmeasurements.

For strain gage weight sensing, the frequency of interrogation would beconsiderably higher than that of the tire monitor, for example. However,if the seat is unoccupied, then the frequency of interrogation can besubstantially reduced. For an occupied seat, information as to theidentity and/or category and position of an occupying item of the seatcan be obtained through the multiple weight sensors described. For thisreason, and due to the fact that during the pre-crash event, theposition of an occupying item of the seat may be changing rapidly,interrogations as frequently as once every 10 milliseconds or faster canbe desirable. This would also enable a distribution of the weight beingapplied to the seat to be obtained which provides an estimation of theposition of the object occupying the seat. Using pattern recognitiontechnology, e.g., a trained neural network, sensor fusion, fuzzy logic,etc., the identification of the object can be ascertained based on thedetermined weight and/or determined weight distribution.

There are many other methods by which SAW devices can be used todetermine the weight and/or weight distribution of an occupying itemother than the methods described above and all such uses of SAW strainsensors for determining the weight and weight distribution of anoccupant are contemplated. For example, SAW devices with appropriatestraps can be used to measure the deflection of the seat cushion top orbottom caused by an occupying item, or if placed on the seat belts, theload on the belts can determined wirelessly and powerlessly. Geometriessimilar to those disclosed in U.S. Pat. No. 6,242,701 (which disclosesmultiple strain gage geometries) using SAW strain-measuring devices canalso be constructed, e.g., any of the multiple strain gage geometriesshown therein.

Although a preferred method for using the invention is to interrogateeach of the SAW devices using wireless means, in some cases it may bedesirable to supply power to and/or obtain information from one or moreof the devices using wires. As such, the wires would be an optionalfeature.

One advantage of the weight sensors of at least one of the inventionsdisclosed herein along with the geometries disclosed in the '701 patentand herein below, is that in addition to the axial stress in the seatsupport, the bending moments in the structure can be readily determined.For example, if a seat is supported by four “legs”, it is possible todetermine the state of stress, assuming that axial twisting can beignored, using four strain gages on each leg support for a total ofsixteen such gages. If the seat is supported by three legs, then thiscan be reduced to twelve. Naturally, a three-legged support ispreferable than four since with four, the seat support isover-determined severely complicating the determination of the stresscaused by an object on the seat. Even with three supports, stresses canbe introduced depending on the nature of the support at the seat railsor other floor-mounted supporting structure. If simple supports are usedthat do not introduce bending moments into the structure, then thenumber of gages per seat can be reduced to three providing a good modelof the seat structure is available. Unfortunately, this is usually notthe case and most seats have four supports and the attachments to thevehicle not only introduce bending moments into the structure but thesemoments vary from one position to another and with temperature. The SAWstrain gages of at least one of the inventions disclosed herein lendthemselves to the placement of multiple gages onto each support asneeded to approximately determine the state of stress and thus theweight of the occupant depending on the particular vehicle application.Furthermore, the wireless nature of these gages greatly simplifies theplacement of such gages at those locations that are most appropriate.

One additional point should be mentioned. In many cases, thedetermination of the weight of an occupant from the static strain gagereadings yields inaccurate results due to the indeterminate stress statein the support structure. However, the dynamic stresses to a first orderare independent of the residual stress state. Thus, the change in stressthat occurs as a vehicle travels down a roadway caused by dips in theroadway can provide an accurate measurement of the weight of an objectin a seat. This is especially true if an accelerometer is used tomeasure the vertical excitation provided to the seat.

4.2 Bladder Weight Sensors

One embodiment of a weight sensor and method for determining the weightof an occupant of a seat, which may be used in the methods and apparatusfor adjusting a vehicle component and identifying an occupant of a seat,comprises a bladder having at least one chamber adapted to be arrangedin a seat portion of the seat, and at least one transducer for measuringthe pressure in a respective chamber. The bladder may comprise aplurality of chambers, each adapted to be arranged at a differentlocation in the seat portion of the seat. Thus, it is possible todetermine the weight distribution of the occupant using this weightsensor with several transducers whereby each transducer is associatedwith one chamber and the weight distribution of the occupant is obtainedfrom the pressure measurements of the transducers. The position of theoccupant and the center of gravity of the occupant can also bedetermined by one skilled in the art based on the weight distribution.

With knowledge of the weight of an occupant, additional improvements canbe made to automobile and truck seat designs. In particular, thestiffness of the seat can be adjusted so as to provide the same level ofcomfort for light and for heavy occupants. The damping of occupantmotions, which previously has been largely neglected, can also bereadily adjusted as shown on FIG. 25 which is a view of the seat of FIG.24 showing one of several possible arrangements for changing thestiffness and the damping of the seat. In the seat bottom 250, there isa container 251, the conventional foam and spring design has beenreplaced by an inflated rectangular container very much like an airmattress which contains a cylindrical inner container 252 which isfilled with an open cell urethane foam, for example, or other meanswhich constrain the flow of air therein. An adjustable orifice 253connects the two containers both of which can be bladders 251, 252 sothat air, or other fluid, can flow in a controlled manner therebetween.The amount of opening of orifice 253 is controlled by control circuit254. A small air compressor, or fluid pump, 255 controls the pressure incontainer 251 under control of the control circuit 254. A pressuretransducer 256 monitors the pressure within container 251 and inputsthis information into control circuit 254.

The operation of the system is as follows. When an occupant sits on theseat, pressure initially builds up in the seat container or bladder 251which gives an accurate measurement of the weight of the occupant.Control circuit 254, using an algorithm and a microprocessor, thendetermines an appropriate stiffness for the seat and adds pressure toachieve that stiffness. The pressure equalizes between the twocontainers 251 and 252 through the flow of fluid through orifice 253.Control circuit 254 also determines an appropriate damping for theoccupant and adjusts the orifice 253 to achieve that damping. As thevehicle travels down the road and the road roughness causes the seat tomove up and down, the inertial force on the seat by the occupant causesthe fluid pressure to rise and fall in container 252 and also, but, muchless so, in container 251 since the occupant sits mainly above container252 and container 251 is much larger than container 252. The majordeflection in the seat takes place first in container 252 whichpressurizes and transfers fluid to container 251 through orifice 253.The size of the orifice opening determines the flow rate between the twocontainers 251, 252 and therefore the damping of the motion of theoccupant. Since this opening is controlled by control circuit 254, theamount of damping can thereby also be controlled. Thus, in this simplestructure, both the stiffness and damping can be controlled to optimizethe seat for a particular driver. Naturally, if the driver does not likethe settings made by control circuit 254, he or she can change them toprovide a stiffer or softer ride. When fluid is used above, it can meana gas, liquid, gel or other flowable medium.

The stiffness of a seat is the change in force divided by the change indeflection. This is important for many reasons, one of which is that itcontrols the natural vibration frequency of the seat occupantcombination. It is important that this be different from the frequencyof vibrations which are transmitted to the seat from the vehicle inorder to minimize the up and down motions of the occupant. The dampingis a force which opposes the motion of the occupant and which isdependent on the velocity of relative motion between the occupant andthe seat bottom. It thus removes energy and minimizes the oscillatorymotion of the occupant. These factors are especially important in truckswhere the vibratory motions of the driver's seat, and thus the driver,have caused many serious back injuries among truck drivers.

In FIG. 25, the airbag or bladder 241 which interacts with the occupantis shown with a single chamber. Naturally, bladder 241 can be composedof multiple chambers 241 a, 241 b, 241 c, and 241 d as shown in FIG.25A. The use of multiple chambers permits the weight distribution of theoccupant to be determined if a separate pressure transducer is used ineach cell of the bladder, or if a single gage is switched from chamberto chamber. Such a scheme gives the opportunity of determining to someextent the position of the occupant on the seat or at least the positionof the center of gravity of the occupant. Naturally, more than fourchambers can be used.

Any one of a number of known pressure measuring sensors can be used withthe bladder weight sensor disclosed herein. One particular technologythat has been developed for measuring the pressure in a rotating tireuses surface acoustic wave (SAW) technology and has the advantage thatthe sensor is wireless and powerless. Thus, the sensor does not need abattery nor is it required to run wires from the sensor to controlcircuitry. An interrogator is provided that transmits an RF signal tothe sensor and receives a return signal that contains the temperatureand pressure of the fluid within the bladder. The interrogator can bethe same one that is used for tire pressure monitoring thus making thisSAW system very inexpensive to implement and easily expandable toseveral seats within the vehicle. The switches that control the seat canalso now be made wireless using SAW technology and thus they can beplaced at any convenient location such as the vehicle door-mountedarmrest without requiring wires to connect the switch to the seatmotors. Other uses of SAW technology are discussed in the currentassignee's U.S. Pat. No. 6,662,642. Although a SAW device has beendescribed above, an equivalent system can be constructed using RFID typetechnology where the interrogator transmits sufficient RF energy topower the RFID circuit. This generally requires that the interrogatorantenna be closer to the device antenna than in the case of SAW devicesbut the interrogator circuitry is generally simpler and thus lessexpensive. Also energy harvesting can also be used to provide energy torun the RFID circuit or to boost the SAW circuit.

In the description above, the air is the preferred use as the fluid tofill the bladder 241. In some cases, especially where damping andnatural frequency control is not needed, another fluid such as a liquidor jell could be used to fill the bladder 241. In addition to silicone,candidate liquids include ethylene glycol or other low freezing pointliquids.

In an apparatus for adjusting the stiffness of a seat in a vehicle, atleast two containers are arranged in or near a bottom portion of theseat, the first container substantially supports the load of a seatoccupant and the second container is relatively unaffected by this load.The two containers are in flow communication with each other through avariable flow passage. Insertion means, e.g., an air compressor or fluidpump, are provided for directing a medium into one of the container andmonitoring means, e.g., a pressure transducer, measuring the pressure inone or both containers. A control circuit is coupled to the mediuminsertion means and the monitoring means for regulating flow of mediuminto the first container via the medium insertion means until thepressure in the first container as measured by the monitoring means isindicative of a desired stiffness for the seat. The control circuit mayalso be arranged to adjust the flow passage to thereby control flow ofmedium between the two containers and thus damping the motion of onobject on the seat. The flow passage may be an orifice in a peripheralwall of the inner container.

A method for adjusting the stiffness of a seat in a vehicle comprisesthe steps of arranging a first container in a bottom portion of the seatand subjected to the load on the seat, arranging a second container in aposition where it is relatively unaffected by the load on the seat,coupling interior volumes of the two containers through a variable flowpassage, measuring the pressure in the first container, and introducingmedium into the first container until the measured pressure in the firstcontainer is indicative of a desired stiffness for the seat.

4.3 Dynamic Weight Sensing

The combination of the outputs from these accelerometer sensors and theoutput of strain gage weight sensors in a vehicle seat, or in or on asupport structure of the seat, can be used to make an accurateassessment of the occupancy of the seat and differentiate betweenanimate and inanimate occupants as well as determining where in the seatthe occupants are sitting and the state of the use of the seatbelt. Thiscan be done by observing the acceleration signals from the sensors ofFIG. 141 of the '881 application and simultaneously the dynamic straingage measurements from seat-mounted strain gages. The accelerometersprovide the input function to the seat and the strain gages measure thereaction of the occupying item to the vehicle acceleration and therebyprovide a method of determining dynamically the mass of the occupyingitem and its location. This is particularly important during occupantposition sensing during a crash event. By combining the outputs of theaccelerometers and the strain gages and appropriately processing thesame, the mass and weight of an object occupying the seat can bedetermined as well as the gross motion of such an object so that anassessment can be made as to whether the object is a life form such as ahuman being.

Several ways to process the acceleration signal and the stain orpressure signal are discussed with reference to FIG. 167 in the '881application. In general, the dynamic load applied to the seat ismeasured or a forcing function of the seat is measured, as a function ofthe acceleration signal. This represents the effect of the movement ofthe vehicle on the occupant which is reflected in the measurement ofweight by the strain or pressure gages. Thus, the measurement obtainedby the strain or pressure gages can be considered to have twocomponents, one component resulting from the weight applied by theoccupant in a stationary state of the vehicle and the other arising orresulting from the movement of the vehicle. The vehicle-movementcomponent can be separated from the total strain or pressure gagemeasurement to provide a more accurate indication of the weight of theoccupant.

4.4 Combined Spatial and Weight

A novel occupant position sensor for a vehicle, for determining theposition of the occupant, comprises a weight sensor for determining theweight of an occupant of a seat as described immediately above andprocessor means for receiving the determined weight of the occupant fromthe weight sensor and determining the position of the occupant based atleast in part on the determined weight of the occupant. The position ofthe occupant could also be determined based in part on waves receivedfrom the space above the seat, data from seat position sensors,reclining angle sensors, etc.

Although spatial sensors such as ultrasonic, electric field and opticaloccupant sensors can accurately identify and determine the location ofan occupying item in the vehicle, a determination of the mass of theitem is less accurate as it can be fooled in some cases by a thick butlight winter coat, for example. Therefore, it is desirable, when theeconomics permit, to provide a combined system that includes both weightand spatial sensors. Such a system permits a fine tuning of thedeployment time and the amount of gas in the airbag to match theposition and the mass of the occupant. If this is coupled with a smartcrash severity sensor, then a true smart airbag system can result, asdisclosed in the current assignee's U.S. Pat. No. 6,532,408.

As disclosed in several of the current assignee's patents, referencedherein and others, the combination of a reduced number of transducersincluding weight and spatial can result from a pruning process startingfrom a larger number of sensors. For example, such a process can beginwith four load cells and four ultrasonic sensors and after a pruningprocess, a system containing two ultrasonic sensors and one load cellcan result. At least one of the inventions disclosed herein is thereforenot limited to any particular number or combination of sensors and theoptimum choice for a particular vehicle will depend on many factorsincluding the specifications of the vehicle manufacturer, cost, accuracydesired, availability of mounting locations and the chosen technologies.

4.5 Face Recognition

A neural network, or other pattern recognition system, can be trained torecognize certain people as permitted operators of a vehicle or forgranting access to a cargo container or truck trailer. In this case, ifa non-recognized person attempts to operate the vehicle or to gainaccess, the system can disable the vehicle and/or sound an alarm or senda message to a remote site via telematics. Since it is unlikely that anunauthorized operator will resemble the authorized operator, the neuralnetwork system can be quite tolerant of differences in appearance of theoperator. The system defaults to where a key or other identificationsystem must be used in the case that the system doesn't recognize theoperator or the owner wishes to allow another person to operate thevehicle or have access to the container. The transducers used toidentify the operator can be any of the types described in detail above.A preferred method is to use optical imager-based transducers perhaps inconjunction with a weight sensor for automotive applications. This isnecessary due to the small size of the features that need to berecognized for a high accuracy of recognition. An alternate system usesan infrared laser, which can be modulated to provide three-dimensionalmeasurements, to irradiate or illuminate the operator and a CCD or CMOSdevice to receive the reflected image. In this case, the recognition ofthe operator is accomplished using a pattern recognition system such asdescribed in Popesco, V. and Vincent, J. M. “Location of Facial FeaturesUsing a Boltzmann Machine to Implement Geometric Constraints”, Chapter14 of Lisboa, P. J. G. and Taylor, M. J. Editors, Techniques andApplications of Neural Networks, Ellis Horwood Publishers, New York,1993. In the present case, a larger CCD element array containing 50,000or more elements would typically be used instead of the 16 by 16 or 256element CCD array used by Popesco and Vincent.

FIG. 16 shows a schematic illustration of a system for controllingoperation of a vehicle based on recognition of an authorized individualin accordance with the invention. A similar system can be designed forallowing access to a truck trailer, cargo container or railroad car, forexample. One or more images of the passenger compartment 260 arereceived at 261 and data derived therefrom at 262. Multiple imagereceivers may be provided at different locations. The data derivationmay entail any one or more of numerous types of image processingtechniques such as those described in the current assignee's U.S. Pat.No. 6,397,136 including those designed to improve the clarity of theimage. A pattern recognition algorithm, e.g., a neural network, istrained in a training phase 263 to recognize authorized individuals. Thetraining phase can be conducted upon purchase of the vehicle by thedealer or by the owner after performing certain procedures provided tothe owner, e.g., entry of a security code or key or at anotherappropriate time and place. In the training phase for a theft preventionsystem, the authorized operator(s) would sit themselves in the passengerseat and optical images would be taken and processed to obtain thepattern recognition algorithm. Alternately, the training can be doneaway from the vehicle which would be more appropriate for cargocontainers and the like.

A processor 264 is embodied with the pattern recognition algorithm thustrained to identify whether a person is the authorized individual byanalysis of subsequently obtained data derived from optical images 262.The pattern recognition algorithm in processor 264 outputs an indicationof whether the person in the image is an authorized individual for whichthe system is trained to identify. A security system 265 enablesoperations of the vehicle when the pattern recognition algorithmprovides an indication that the person is an individual authorized tooperate the vehicle and prevents operation of the vehicle when thepattern recognition algorithm does not provide an indication that theperson is an individual authorized to operate the vehicle.

In some cases, the recognition system can be substantially improved ifdifferent parts of the electromagnetic spectrum are used. As taught inthe book Alien Vision referenced above, distinctive facial markings areevident when viewed under near UV or MWIR illumination that can be usedto positively identify a person. Other biometric measures can be usedwith, or in place of, a facial or iris image to further improve therecognition accuracy such as voice recognition (voice-print), finger orhand prints, weight, height, arm length, hand size etc.

Instead of a security system, another component in the vehicle can beaffected or controlled based on the recognition of a particularindividual. For example, the rear view mirror, seat, seat belt anchoragepoint, headrest, pedals, steering wheel, entertainment system,air-conditioning/ventilation system can be adjusted. Additionally, thedoor can be unlocked upon approach of an authorized person.

FIG. 17 is a schematic illustration of a method for controllingoperation of a vehicle based on recognition of a person as one of a setof authorized individuals. Although the method is described and shownfor permitting or preventing ignition of the vehicle based onrecognition of an authorized driver, it can be used to control for anyvehicle component, system or subsystem based on recognition of anindividual.

Initially, the system is set in a training phase 266 in which images,and other biometric measures, including the authorized individuals areobtained by means of at least one optical receiving unit 267 and apattern recognition algorithm is trained based thereon 268, usuallyafter application of one or more image processing techniques to theimages. The authorized individual(s) occupy the passenger compartment,or some other appropriate location, and have their picture taken by theoptical receiving unit to enable the formation of a database on whichthe pattern recognition algorithm is trained. Training can be performedby any known method in the art, although combination neural networks arepreferred.

The system is then set in an operational phase 269 wherein an image isoperatively obtained 270, including the driver when the system is usedfor a security system. If the system is used for component adjustment,then the image would include any passengers or other occupying items inthe vehicle. The obtained image, or images if multiple optical receivingunits are used, plus other biometric information, are input into thepattern recognition algorithm 271, preferably after some imageprocessing, and a determination is made whether the pattern recognitionalgorithm indicates that the image includes an authorized driver 272. Ifso, ignition, or some other system, of the vehicle is enabled 273, orthe vehicle may actually be started automatically. If not, an alarm issounded and/or the police or other remote site may be contacted 274.

Once an optic-based system is present in a vehicle, other options can beenabled such as eye-tracking as a data input device or to detectdrowsiness, as discussed above, and even lip reading as a data inputdevice or to augment voice input. This is discussed, for example,Eisenberg, Anne, “Beyond Voice Recognition to a Computer That ReadsLips”, New York Times, Sep. 11, 2003. Lip reading can be implemented ina vehicle through the use of IR illumination and training of a patternrecognition algorithm, such as a neural network or a combinationnetwork. This is one example of where an adaptive neural or combinationnetwork can be employed that learns as it gains experience with aparticular driver. The word “radio”, for example, can be associated withlip motions when the vehicle is stopped or moving slowly and then at alater time when the vehicle is traveling at high speed with considerablewind noise, the voice might be difficult for the system to understand.When augmented with lip reading, the word “radio” can be more accuratelyrecognized. Thus, the combination of lip reading and voice recognitioncan work together to significantly improve accuracy.

Face recognition can of course be done in two or three dimensions andcan involve the creation of a model of the person's head that can aidwhen illumination is poor, for example. Three dimensions are availableif multiple two dimensional images are acquired as the occupant moveshis or her head or through the use of a three-dimensional camera. Athree-dimensional camera generally has two spaced-apart lenses plussoftware to combine the two views. Normally, the lenses are relativelyclose together but this may not need to be the case and significantlymore information can be acquired if the lenses are spaced further apartand in some cases, even such that one camera has a frontal view and theother a side view, for example. Naturally, the software is complicatedfor such cases but the system becomes more robust and less likely to beblocked by a newspaper, for example. A scanning laser radar, PMD orsimilar system with a modulated beam or with range gating as describedabove can also be used to obtain three-dimensional information or a 3Dimage.

Eye tracking as disclosed in Jacob, “Eye Tracking in Advanced InterfaceDesign”, Robert J. K. Jacob, Human-Computer Interaction Lab, NavalResearch Laboratory, Washington, D.C., can be used by vehicle operatorto control various vehicle components such as the turn signal, lights,radio, air conditioning, telephone, Internet interactive commands, etc.much as described in U.S. patent application Ser. No. 09/645,709. Thedisplay used for the eye tracker can be a heads-up display reflectedfrom the windshield or it can be a plastic electronics display locatedeither in the visor or the windshield.

The eye tracker works most effectively in dim light where the driver'seyes are sufficiently open that the cornea and retina are clearlydistinguishable. The direction of operator's gaze is determined bycalculation of the center of pupil and the center of the iris that arefound by illuminating the eye with infrared radiation. FIG. 8Eillustrates a suitable arrangement for illuminating eye along the sameaxis as the pupil camera. The location of occupant's eyes must be firstdetermined as described elsewhere herein before eye tracking can beimplemented. In FIG. 8E, imager system 52, 54, or 56 are candidatelocations for eye tracker hardware.

The technique is to shine a collimated beam of infrared light on to beoperator's eyeball producing a bright corneal reflection can be brightpupil reflection. Imaging software analyzes the image to identify thelarge bright circle that is the pupil and a still brighter dot which isthe corneal reflection and computes the center of each of these objects.The line of the gaze is determined by connecting the centers of thesetwo reflections.

It is usually necessary only to track a single eye as both eyes tend tolook at the same object. In fact, by checking that both eyes are lookingat the same object, many errors caused by the occupant looking throughthe display onto the road or surrounding environment can be eliminatedObject selection with a mouse or mouse pad, as disclosed in the '709application cross-referenced above is accomplished by pointing at theobject and depressing a button. Using eye tracking, an additionaltechnique is available based on the length of time the operator gazes atthe object. In the implementations herein, both techniques areavailable. In the simulated mouse case, the operator gazes at an object,such as the air conditioning control, and depresses a button on thesteering wheel, for example, to select the object. Alternately, theoperator merely gazes at the object for perhaps one-half second and theobject is automatically selected. Both techniques can be implementedsimultaneously allowing the operator to freely choose between them. Thedwell time can be selectable by the operator as an additional option.Typically, the dwell times will range from about 0.1 seconds to about 1second.

The problem of finding the eyes and tracking the head of the driver, forexample, is handled in Smeraldi, F., Carmona, J. B., “Saccadic searchwith Garbor features applied to eye detection and real-time headtracking”, Image and Vision Computing 18 (2000) 323-329, ElsevierScience B.V. The Saccadic system described is a very efficient method oflocating the most distinctive part of a persons face, the eyes, and inaddition to finding the eyes, a modification of the system can be usedto recognize the driver. The system makes use of the motion of thesubject's head to locate the head prior to doing a search for the eyesusing a modified Garbor decomposition method. By comparing twoconsecutive frames, the head can usually be located if it is in thefield of view of the camera. Although this is the preferred method,other eye location and tracking methods can also be used as reported inthe literature and familiar to those skilled in the art.

4.6 Heartbeat and Health State

In addition to the use of transducers to determine the presence andlocation of occupants in a vehicle, other sensors can also be used. Forexample, as discussed above, a heartbeat sensor, which determines thenumber and presence of heartbeats, can also be arranged in the vehicle.Heartbeat sensors can be adapted to differentiate between a heartbeat ofan adult, a heartbeat of a child and a heartbeat of an animal. As itsname implies, a heartbeat sensor detects a heartbeat, and the magnitudethereof, of a human occupant of the seat or other position, if such ahuman occupant is present. The output of the heartbeat sensor is inputto the processor of the interior monitoring system. One heartbeat sensorfor use in the invention may be of the types as disclosed in McEwan inU.S. Pat. No. 5,573,012 and U.S. Pat. No. 5,766,208. The heartbeatsensor can be positioned at any convenient position relative to theseats or other appropriate location where occupancy is being monitored.A preferred automotive location is within the vehicle seatback.

This type of micropower impulse radar (MIR) sensor is not believed tohave been used in an interior monitoring system in the past. It can beused to determine the motion of an occupant and thus can determine hisor her heartbeat (as evidenced by motion of the chest), for example.Such an MIR sensor can also be arranged to detect motion in a particulararea in which the occupant's chest would most likely be situated orcould be coupled to an arrangement which determines the location of theoccupant's chest and then adjusts the operational field of the MIRsensor based on the determined location of the occupant's chest. Amotion sensor utilizing a micro-power impulse radar (MIR) system asdisclosed, for example, in McEwan U.S. Pat. No. 5,361,070, as well asmany other patents by the same inventor. Motion sensing is accomplishedby monitoring a particular range from the sensor as disclosed in thatpatent. MIR is one form of radar that has applicability to occupantsensing and can be mounted at various locations in the vehicle. Otherforms include, among others, ultra wideband (UWB) by the Time DomainCorporation and noise radar (NR) by Professor Konstantin Lukin of theNational Academy of Sciences of Ukraine Institute of Radiophysics andElectronics. Radar has an advantage over ultrasonic sensors in that datacan be acquired at a higher speed and thus the motion of an occupant canbe more easily tracked. The ability to obtain returns over the entireoccupancy range is somewhat more difficult than with ultrasoundresulting in a more expensive system overall. MIR, UWB or NR haveadditional advantages in their lack of sensitivity to temperaturevariation and have a comparable resolution to about 40 kHz ultrasound.Resolution comparable to higher frequency is of course possible usingmillimeter waves, for example. Additionally, multiple MIR, UWB or NRsensors can be used when high-speed tracking of the motion of anoccupant during a crash is required since they can be individuallypulsed without interfering with each other through frequency, time orcode division multiplexing or other multiplexing schemes.

Other methods have been reported for measuring heartbeat includingvibrations introduced into a vehicle and variations in the electricfield in the vicinity of where an occupant might reside. All suchmethods are considered encompassed by the teachings of at least one ofthe inventions disclosed herein. The detection of a heartbeat regardlessof how it is accomplished is indicative of the presence of a livingbeing within the vehicle and such a detection as part of an occupantpresence detection system is novel to at least one of the inventionsdisclosed herein. Similarly, any motion of an object that is not inducedby the motion of the vehicle itself is indicative of the presence of aliving being and thus part of the teachings herein. The sensing ofoccupant motion regardless of how it is accomplished when used in asystem to affect another vehicle system is contemplated herein.

5. Telematics

Some of the inventions herein relate generally to telematics and thetransmission of information from a vehicle to one or more remote siteswhich can react to the position or status of the vehicle and/oroccupant(s) therein.

Initially, sensing of the occupancy of the vehicle and the optionaltransmission of this information, which may include images, to remotelocations will be discussed. This entails obtaining information fromvarious sensors about the occupants in the passenger compartment of thevehicle, e.g., the number of occupants, their type and their motion, ifany. Then, the concept of a low cost automatic crash notification systemwill be discussed. Next, a diversion into improvements in cell phoneswill be discussed followed by a discussion of trapped children and howtelematics can help save their lives. Finally, the use of telematicswith non-automotive vehicles will round out this section.

Elsewhere in the parent '881 application, e.g., section 13, the use oftelematics is described with a discussion of general vehicle diagnosticmethods with the diagnosis being transmittable via a communicationsdevice to the remote locations. The diagnostics section includes anextensive discussion of various sensors for use on the vehicle to sensedifferent operating parameters and conditions of the vehicle isprovided. All of the sensors discussed herein can be coupled to acommunications device enabling transmission of data, signals and/orimages to the remote locations, and reception of the same from theremote locations.

5.1 Transmission of Occupancy Information

The cellular phone system, or other telematics communication device, isshown schematically in FIG. 2 by box 32 and outputs to an antenna 34.The phone system or telematics communication device 34 can be coupled tothe vehicle interior monitoring system in accordance with any of theembodiments disclosed herein and serves to establish a communicationschannel with one or more remote assistance facilities, such as an EMSfacility or dispatch facility from which emergency response personnelare dispatched. The telematics system can also be a satellite-basedsystem such as provided by Skybitz.

In the event of an accident, the electronic system associated with thetelematics system interrogates the various interior monitoring systemmemories in processor 20 and can arrive at a count of the number ofoccupants in the vehicle, if each seat is monitored, and, in moresophisticated systems, even makes a determination as to whether eachoccupant was wearing a seatbelt and if he or she is moving after theaccident, and/or the health state of one or more of the occupants asdescribed above, for example. The telematics communication system thenautomatically notifies an EMS operator (such as 911, OnStar® orequivalent) and the information obtained from the interior monitoringsystems is forwarded so that a determination can be made as to thenumber of ambulances and other equipment to send to the accident site.Vehicles having the capability of notifying EMS in the event one or moreairbags deployed are now in service but are not believed to use any ofthe innovative interior monitoring systems described herein. Suchvehicles will also have a system, such as the global positioning system,which permits the vehicle to determine its location and to forward thisinformation to the EMS operator.

FIG. 35 shows a schematic diagram of an embodiment of the inventionincluding a system for determining the presence and health state of anyoccupants of the vehicle and a telecommunications link. This embodimentincludes means for determining the presence of any occupants 150 whichmay take the form of a heartbeat sensor, chemical sensor and/or motionsensor as described above and means for determining the health state ofany occupants 151 as discussed above. The latter means may be integratedinto the means for determining the presence of any occupants, i.e., oneand the same component, or separate therefrom. Further, means fordetermining the location, and optionally velocity, of the occupantsand/or one or more parts thereof 152 are provided and may be anyconventional occupant position sensor or preferably, one of the occupantposition sensors as described herein (e.g., those utilizing waves.electromagnetic radiation, electric fields, bladders, strain gages etc.)or as described in the current assignee's patents and patentapplications referenced above.

A processor 153 is coupled to the presence determining means 150, thehealth state determining means 151 and the location determining means152. A communications unit 154 is coupled to the processor 153. Theprocessor 153 and/or communications unit 154 can also be coupled tomicrophones 158 that can be distributed throughout the vehicle andinclude voice-processing circuitry to enable the occupant(s) to effectvocal control of the processor 153, communications unit 154 or anycoupled component or oral communications via the communications unit154. The processor 153 is also coupled to another vehicular system,component or subsystem 155 and can issue control commands to effectadjustment of the operating conditions of the system, component orsubsystem. Such a system, component or subsystem can be the heating orair-conditioning system, the entertainment system, an occupant restraintdevice such as an airbag, a glare prevention system, etc. Also, apositioning system 156 could be coupled to the processor 153 andprovides an indication of the absolute position of the vehicle,preferably using satellite-based positioning technology (e.g., a GPSreceiver).

In normal use (other then after a crash), the presence determining means150 determine whether any human occupants are present, i.e., adults orchildren, and the location determining means 152 determine theoccupant's location. The processor 153 receives signals representativeof the presence of occupants and their location and determines whetherthe vehicular system, component or subsystem 155 can be modified tooptimize its operation for the specific arrangement of occupants. Forexample, if the processor 153 determines that only the front seats inthe vehicle are occupied, it could control the heating system to provideheat only through vents situated to provide heat for the front-seatedoccupants.

The communications unit 154 performs the function of enablingestablishment of a communications channel to a remote facility toreceive information about the occupancy of the vehicle as determined bythe presence determining means 150, occupant health state determiningmeans 151 and/or occupant location determining means 152. Thecommunications unit 154 thus can be designed to transmit over asufficiently large range and at an established frequency monitored bythe remote facility, which may be an EMS facility, sheriff department,or fire department. Alternately, it can communicate with a satellitesystem such as the Skybitz system and the information can be forwardedto the appropriate facility via the Internet or other appropriate link.

Another vehicular telematics system, component or subsystem is anavigational aid, such as a route guidance display or map. In this case,the position of the vehicle as determined by the positioning system 156is conveyed through processor 153 to the communications unit 154 to aremote facility and a map is transmitted from this facility to thevehicle to be displayed on the route display. If directions are needed,a request for such directions can be entered into an input unit 157associated with the processor 153 and transmitted to the facility. Datafor the display map and/or vocal instructions can then be transmittedfrom this facility to the vehicle.

Moreover, using this embodiment, it is possible to remotely monitor thehealth state of the occupants in the vehicle and most importantly, thedriver. The health state determining means 151 may be used to detectwhether the driver's breathing is erratic or indicative of a state inwhich the driver is dozing off. The health state determining means 151can also include a breath-analyzer to determine whether the driver'sbreath contains alcohol. In this case, the health state of the driver isrelayed through the processor 153 and the communications unit 154 to theremote facility and appropriate action can be taken. For example, itwould be possible to transmit a command, e.g., in the form of a signal,to the vehicle to activate an alarm or illuminate a warning light or ifthe vehicle is equipped with an automatic guidance system and ignitionshut-off, to cause the vehicle to come to a stop on the shoulder of theroadway or elsewhere out of the traffic stream. The alarm, warninglight, automatic guidance system and ignition shut-off are thusparticular vehicular components or subsystems represented by 155. Thevehicular component or subsystem could be activated directly by thesignal from the remote facility, if they include a signal receiver, orindirectly via the communications unit 154 and processor 153.

In use after a crash, the presence determining means 150, health statedetermining means 151 and location determining means 152 obtain readingsfrom the passenger compartment and direct such readings to the processor153. The processor 153 analyzes the information and directs or controlsthe transmission of the information about the occupant(s) to a remote,manned facility. Such information could include the number and type ofoccupants, i.e., adults, children, infants, whether any of the occupantshave stopped breathing or are breathing erratically, whether theoccupants are conscious (as evidenced by, e.g., eye motion), whetherblood is present (as detected by a chemical sensor) and whether theoccupants are making sounds (as detected by a microphone). Thedetermination of the number of occupants is obtained from the presencedetermining mechanism 150, i.e., the number of occupants whose presenceis detected is the number of occupants in the passenger compartment. Thedetermination of the status of the occupants, i.e., whether they aremoving is performed by the health state determining mechanism 151, suchas the motion sensors, heartbeat sensors, chemical sensors, etc.Moreover, the communications link through the communications unit 154can be activated immediately after the crash to enable personnel at theremote facility to initiate communications with the vehicle.

Once an occupying item has been located in a vehicle, or any objectoutside of the vehicle, the identification or categorization informationalong with an image, including an IR or multispectral image, or icon ofthe object can be sent via a telematics channel to a remote location. Apassing vehicle, for example, can send a picture of an accident or asystem in a vehicle that has had an accident can send an image of theoccupant(s) of the vehicle to aid in injury assessment by the EMS team.

Although in most if not all of the embodiments described above, it hasbeen assumed that the transmission of images or other data from thevehicle to the EMS or other off-vehicle (remote) site is initiated bythe vehicle, this may not always be the case and in some embodiments,provision is made for the off-vehicle site to initiate the acquisitionand/or transmission of data including images from the vehicle. Thus, forexample, once an EMS operator knows that there has been an accident, heor she can send a command to the vehicle to control components in thevehicle to cause the components send images and other data so that thesituation can be monitored by the operator or other person. Thecapability to receive and initiate such transmissions can also beprovided in an emergency vehicle such as a police car or ambulance. Inthis manner, for a stolen vehicle situation, the police officer, forexample, can continue to monitor the interior of the stolen vehicle.

FIG. 36 shows a schematic of the integration of the occupant sensingwith a telematics link and the vehicle diagnosis with a telematics link.As envisioned, the occupant sensing system 600 includes those componentswhich determine the presence, position, health state, and otherinformation relating to the occupants, for example the transducersdiscussed above with reference to FIGS. 1, 2 and 35 and the SAW devicediscussed above with reference to FIG. 135 of the '881 application.Information relating to the occupants includes information as to whatthe driver is doing, talking on the phone, communicating with OnStar® orother route guidance, listening to the radio, sleeping, drunk, drugged,having a heart attack The occupant sensing system may also be any ofthose systems and apparatus described in any of the current assignee'sabove-referenced patents and patent applications or any other comparableoccupant sensing system which performs any or all of the same functionsas they relate to occupant sensing. Examples of sensors which might beinstalled on a vehicle and constitute the occupant sensing systeminclude heartbeat sensors, motion sensors, weight sensors, microphonesand optical sensors.

A crash sensor system 591 is provided and determines when the vehicleexperiences a crash. This crash sensor may be part of the occupantrestraint system or independent from it. Crash sensor system 591 mayinclude any type of crash sensors, including one or more crash sensorsof the same or different types.

Vehicle sensors 592 include sensors which detect the operatingconditions of the vehicle such as those sensors discussed with referenceto FIGS. 135-138 of the '881 application and tire sensors such asdisclosed in U.S. Pat. No. 6,662,642. Other examples include velocityand acceleration sensors, and angle and angular rate pitch, roll and yawsensors. Of particular importance are sensors that tell what the car isdoing: speed, skidding, sliding, location, communicating with other carsor the infrastructure, etc.

Environment sensors 593 includes sensors which provide data to theoperating environment of the vehicle, e.g., the inside and outsidetemperatures, the time of day, the location of the sun and lights, thelocations of other vehicles, rain, snow, sleet, visibility (fog),general road condition information, pot holes, ice, snow cover, roadvisibility, assessment of traffic, video pictures of an accident, etc.Possible sensors include optical sensors which obtain images of theenvironment surrounding the vehicle, blind spot detectors which providesdata on the blind spot of the driver, automatic cruise control sensorsthat can provide images of vehicles in front of the host vehicle,various radar devices which provide the position of other vehicles andobjects relative to the subject vehicle.

The occupant sensing system 600, crash sensors 591, vehicle sensors 592,environment sensors 593 and all other sensors listed above can becoupled to a communications device 594 which may contain a memory unitand appropriate electrical hardware to communicate with the sensors,process data from the sensors, and transmit data from the sensors. Thememory unit would be useful to store data from the sensors, updatedperiodically, so that such information could be transmitted at set timeintervals.

The communications device 594 can be designed to transmit information toany number of different types of facilities. For example, thecommunications device 594 would be designed to transmit information toan emergency response facility 595 in the event of an accident involvingthe vehicle. The transmission of the information could be triggered by asignal from a crash sensor 591 that the vehicle was experiencing a crashor experienced a crash. The information transmitted could come from theoccupant sensing system 600 so that the emergency response could betailored to the status of the occupants. For example, if the vehicle wasdetermined to have ten occupants, multiple ambulances might be sent.Also, if the occupants are determined not be breathing, then a higherpriority call with living survivors might receive assistance first. Assuch, the information from the occupant sensing system 600 would be usedto prioritize the duties of the emergency response personnel.

Information from the vehicle sensors 592 and environment sensors 593 canalso be transmitted to law enforcement authorities 597 in the event ofan accident so that the cause(s) of the accident could be determined.Such information can also include information from the occupant sensingsystem 600, which might reveal that the driver was talking on the phone,putting on make-up, or another distracting activity, information fromthe vehicle sensors 592 which might reveal a problem with the vehicle,and information from the environment sensors 593 which might reveal theexistence of slippery roads, dense fog and the like.

Information from the occupant sensing system 600, vehicle sensors 592and environment sensors 593 can also be transmitted to the vehiclemanufacturer 598 in the event of an accident so that a determination canbe made as to whether failure of a component of the vehicle caused orcontributed to the cause of the accident. For example, the vehiclesensors might determine that the tire pressure was too low so thatadvice can be disseminated to avoid maintaining the tire pressure toolow in order to avoid an accident. Information from the vehicle sensors592 relating to component failure could be transmitted to adealer/repair facility 596 which could schedule maintenance to correctthe problem.

The communications device 594 can be designed to transmit particularinformation to each site, i.e., only information important to beconsidered by the personnel at that site. For example, the emergencyresponse personnel have no need for the fact that the tire pressure wastoo low but such information is important to the law enforcementauthorities 597 (for the possible purpose of issuing a recall of thetire and/or vehicle) and the vehicle manufacturer 598.

In one exemplifying use of the system shown in FIG. 36, the operator atthe remote facility 595 could be notified when the vehicle experiences acrash, as detected by the crash sensor system 591 and transmitted to theremote facility 595 via the communications device 594. In this case, ifthe vehicle occupants are unable to, or do not, initiate communicationswith the remote facility 595, the operator would be able to receiveinformation from the occupant sensing system 600, as well as the vehiclesensors 592 and environmental sensors 593. The operator could thendirect the appropriate emergency response personnel to the vehicle. Thecommunications device 594 could thus be designed to automaticallyestablish the communications channel with the remote facility when thecrash sensor system 591 determines that the vehicle has experienced acrash.

The communications device 594 can be a cellular phone, OnStar® or othersubscriber-based telematics system, a peer-to-peer vehicle communicationsystem that eventually communicates to the infrastructure and then,perhaps, to the Internet with e-mail to the dealer, manufacturer,vehicle owner, law enforcement authorities or others. It can also be avehicle to LEO or Geostationary satellite system such as Skybitz whichcan then forward the information to the appropriate facility eitherdirectly or through the Internet.

The communication may need to be secret so as not to violate the privacyof the occupants and thus encrypted communication may in many cases berequired. Other innovations described herein include the transmission ofany video data from a vehicle to another vehicle or to a facility remotefrom the vehicle by any means such as a telematics communication systemsuch as OnStar®, a cellular phone system, a communication via GEO,geocentric or other satellite system and any communication thatcommunicates the results of a pattern recognition system analysis. Also,any communication from a vehicle that combines sensor information withlocation information is anticipated by at least one of the inventionsdisclosed herein.

When optical sensors are provided as part of the occupant sensing system600, video conferencing becomes a possibility, whether or not thevehicle experiences a crash. That is, the occupants of the vehicle canengage in a video conference with people at another location 599 viaestablishment of a communications channel by the communications device594.

The vehicle diagnostic system described above using a telematics linkcan transmit information from any type of sensors on the vehicle.

5.2 Telematics with Non-Automotive Vehicles

The transmission of data obtained from imagers, or other transducers, toanother location, requiring the processing of the information, usingneural networks for example, to a remote location is an importantfeature of the inventions disclosed herein. This capability can permitan owner of a cargo container or truck trailer to obtain a picture ofthe interior of the vehicle at any time via telematics. When coupledwith occupant sensing, the driver of a vehicle can be recognized and theresult sent by telematics for authorization to minimize the theft orunauthorized operation of a vehicle. The recognition of the driver caneither be performed on the vehicle or an image of the driver can be sentto a remote location for recognition at that location.

Generally monitoring of containers, trailers, chassis etc. isaccomplished through telecommunications primarily with LEO orgeostationary satellites or through terrestrial-based communicationsystems. These systems are commercially available and will not bediscussed here. Expected future systems include communication betweenthe container and the infrastructure to indicate to the monitoringauthorities that a container with a particular identification number ispassing a particular terrestrial point. If this is expected, then noaction would be taken. The container identification number can be partof a national database that contains information as to the contents ofthe container. Thus, for example, if a container containing hazardousmaterials approaches a bridge or tunnel that forbids such hazardousmaterials from passing over the bridge or through the tunnel, then anemergency situation can be signaled and preventive action taken.

It is expected that monitoring of the transportation of cargo containerswill dramatically increase as the efforts to reduce terrorist activitiesalso increase. If every container that passes within the borders of theUnited States has an identification number and that number is in adatabase that provides the contents of that container, then the use ofshipping containers by terrorists or criminals should gradually beeliminated. If these containers are carefully monitored by satellite oranother communication system that indicates any unusual activity of acontainer, an immediate investigation can result and then the cargotransportation system will gradually approach perfection whereterrorists or criminals are denied this means of transporting materialinto and within the United States. If any container is found containingcontraband material, then the entire history of how that containerentered the United States can be checked to determine the source of thefailure. If the failure is found to have occurred at a loading portoutside of the United States, then sanctions can be imposed on the hostcountry that could have serious effects on that country's ability totrade worldwide. Just the threat of such an action would be asignificant deterrent. Thus, the use of containers to transporthazardous materials or weapons of mass destruction as well as people,narcotics, or other contraband and can be effectively eliminated throughthe use of the container monitoring system of at least one of theinventions disclosed herein.

Prior to the entry of a container ship into a harbor, a Coast Guard boatfrom the U.S. Customs Service can approach the container vessel and scanall of the containers thereon to be sure that all such containers areregistered and tracked including their contents. Where containerscontain dangerous material legally, the seals on those containers can becarefully investigated prior to the ship entering U.S. waters.Obviously, many other security precautions can now be conceived once theability to track all containers and their contents has been achievedaccording to the teachings of at least one of the inventions disclosedherein.

Containers that enter the United States through land ports of entry canalso be interrogated in a similar fashion. As long as the shipper isknown and reputable and the container contents are in the database,which would probably be accessible over the Internet, is properlyupdated, then all containers will be effectively monitored that enterthe United States with the penalty of an error resulting in thedisenfranchisement of the shipper, and perhaps sanctions against thecountry, which for most reputable shippers or shipping companies wouldbe a severe penalty sufficient to cause such shippers or shippingcompanies to take appropriate action to assure the integrity of theshipping containers. Naturally, intelligent selected random inspectionsguided by the container history would still take place.

Although satellite communication is preferred, communication using cellphones and infrastructure devices placed at appropriate locations alongroadways are also possible. Eventually there will be a network linkingall vehicles on the highways in a peer-to-peer arrangement (perhapsusing Bluetooth, IEEE 802.11 (WI-FI), Wi-Mobile or other local, mesh orad-hoc network) at which time information relative to container contentsetc. can be communicated to the Internet or elsewhere through thispeer-to-peer network. It is expected that a pseudo-noise-based orsimilar communication system such as a code division multiple access(CDMA) system, wherein the identifying code of a vehicle is derived fromthe vehicle's GPS determined location, will be the technology of choicefor this peer-to-peer vehicle network. It is expected that this networkwill be able to communicate such information to the Internet (withproper security precautions including encryption where necessary ordesired) and that all of the important information relative to thecontents of moving containers throughout the United States will beavailable on the Internet on a need-to-know basis. Thus, law enforcementagencies can maintain computer programs that will monitor the contentsof containers using information available from the Internet. Similarly,shippers and receivers can monitor the status of their shipments througha connection onto the Internet. Thus, the existence of the Internet orequivalent can be important to the monitoring system described herein.

An alternate method of implementing the invention is to make use of acell phone or PDA. Cell phones that are now sold contain a GPS-basedlocation system as do many PDAs. Such a system along with minimaladditional apparatus can be used to practice the teachings disclosedherein. In this case, the cell phone, PDA or similar portable devicecould be mounted through a snap-in attachment system, for example,wherein the portable device is firmly attached to the vehicle. Thedevice can at that point, for example, obtain an ID number from thecontainer through a variety of methods such as a RFID, SAW or hardwiredbased system. It can also connect to a satellite antenna that wouldpermit the device to communicate to a LEO or GEO satellite system, suchas Skybitz as described above. Since the portable device would onlyoperate on a low duty cycle, the battery should last for many days orperhaps longer. Of course, if it is connected to the vehicle powersystem, its life could be indefinite. Naturally, when power is waning,this fact can be sent to the satellite or cell phone system to alert theappropriate personnel. Since a cell phone contains a microphone, itcould be trained, using an appropriate pattern recognition system, torecognize the sound of an accident or the deployment of an airbag orsimilar event. It thus becomes a very low cost OnStar® type telematicssystem.

As an alternative to using a satellite network, the cell phone networkcan be used in essentially the same manner when a cell phone signal isavailable. Naturally, all of the sensors disclosed herein can either beincorporated into the portable device or placed on the vehicle andconnected to the portable device when the device is attached to thevehicle. This system has a key advantage of avoiding obsolescence. Withtechnology rapidly changing, the portable device can be exchanged for alater model or upgraded as needed or desired, keeping the overall systemat the highest technical state. Existing telematics systems such asOnStar® can of course also be used with this system.

Importantly, an automatic emergency notification system can now be madeavailable to all owners of appropriately configured cell phones, PDAs,or other similar portable devices that can operate on a very low costbasis without the need for a monthly subscription since they can bedesigned to operate only on an exception basis. Owners would pay only asthey use the service. Stolen vehicle location, automatic notification inthe event of a crash even with the transmission of a picture forcamera-equipped devices is now possible. Automatic door unlocking canalso be done by the device since it could transmit a signal to thevehicle, in a similar fashion as a keyless entry system, from eitherinside or outside the vehicle. The phone can be equipped with abiometric identification system such as fingerprint, voice print, facialor iris recognition etc. thereby giving that capability to vehicles. Thedevice can thus become the general key to the vehicle or house, and caneven open the garage door etc. If the cell phone is lost, itswhereabouts can be instantly found since it has a GPS receiver and knowswhere it is. If it is stolen, it will become inoperable without thebiometric identification from the owner.

Other communication systems will also frequently be used to connect thecontainer with the chassis and/or the tractor and perhaps theidentification of the driver or operator. Thus, information can beavailable on the Internet showing what tractor, what trailer, whatcontainer and what driver is operating at a particular time, at aparticular GPS location, on a particular roadway, with what particularcontainer contents. Suitable security will be provided to ensure thatthis information is not freely available to the general public.Naturally, redundancy can be provided to prevent the destruction or anyfailure of a particular site from failing the system.

This communication between the various elements of the shipping systemwhich are co-located (truck, trailer, container, container contents,driver etc.) can be connected through a wired or wireless bus such asthe CAN bus. Also, an electrical system such as disclosed in U.S. Pat.No. 5,809,437, U.S. Pat. No. 6,175,787 and U.S. Pat. No. 6,326,704 canalso be used in the invention.

6. Pattern Recognition

In basic embodiments of the inventions, wave or energy-receivingtransducers are arranged in the vehicle at appropriate locations,associated algorithms are trained, if necessary depending on theparticular embodiment, and function to determine whether a life form, orother object, is present in the vehicle and if so, how many life formsor objects are present. A determination can also be made using thetransducers as to whether the life forms are humans, or morespecifically, adults, child in child seats, etc. As noted above andbelow, this is possible using pattern recognition techniques. Moreover,the processor or processors associated with the transducers can betrained (loaded with a trained pattern recognition algorithm) todetermine the location of the life forms or objects, either periodicallyor continuously or possibly only immediately before, during and after acrash. The location of the life forms or objects can be as general or asspecific as necessary depending on the system requirements, i.e., adetermination can be made that a human is situated on the driver's seatin a normal position (general) or a determination can be made that ahuman is situated on the driver's seat and is leaning forward and/or tothe side at a specific angle as well as determining the position of hisor her extremities and head and chest (specific). Or, a determinationcan be made as to the size or type of objects such as boxes are in atruck trailer or cargo container. The degree of detail is limited byseveral factors, including, e.g., the number, position and type oftransducers and the training of the pattern recognition algorithm.

When different objects are placed on the front passenger seat, theimages (here “image” is used to represent any form of signal) fromtransducers 6, 8, 10 (FIG. 1) are different for different objects butthere are also similarities between all images of rear facing childseats, for example, regardless of where on the vehicle seat it is placedand regardless of what company manufactured the child seat. Alternately,there will be similarities between all images of people sitting on theseat regardless of what they are wearing, their age or size. The problemis to find the set of “rules” or an algorithm that differentiates theimages of one type of object from the images of other types of objects,for example which differentiate the adult occupant images from the rearfacing child seat images or boxes. The similarities of these images forvarious child seats are frequently not obvious to a person looking atplots of the time series from ultrasonic sensors, for example, and thuscomputer algorithms are developed to sort out the various patterns. Fora more detailed discussion of pattern recognition see U.S. Pat. No.RE37260 to Varga et. and discussions elsewhere herein.

The determination of these rules is important to the pattern recognitiontechniques used in at least one of the inventions disclosed herein. Ingeneral, three approaches have been useful, artificial intelligence,fuzzy logic and artificial neural networks including modular orcombination neural networks. Other types of pattern recognitiontechniques may also be used, such as sensor fusion as disclosed inCorrado U.S. Pat. No. 5,482,314, U.S. Pat. No. 5,890,085, and U.S. Pat.No. 6,249,729. In some of the inventions disclosed herein, such as thedetermination that there is an object in the path of a closing window ordoor using acoustics or optics as described herein, the rules aresufficiently obvious that a trained researcher can look at the returnedsignals and devise an algorithm to make the required determinations. Inothers, such as the determination of the presence of a rear facing childseat or of an occupant, artificial neural networks are used to determinethe rules. Neural network software for determining the patternrecognition rules is available from various sources such asInternational Scientific Research, Inc., Panama City, Panama.

The human mind has little problem recognizing faces even when they arepartially occluded such as with a hat, sunglasses or a scarf, forexample. With the increase in low cost computing power, it is nowbecoming possible to train a rather large neural network, perhaps acombination neural network, to recognize most of those cases where ahuman mind will also be successful.

Other techniques which may or may not be part of the process ofdesigning a system for a particular application include the following:

1. Fuzzy logic. Neural networks frequently exhibit the property thatwhen presented with a situation that is totally different from anypreviously encountered, an irrational decision can result. Frequently,when the trained observer looks at input data, certain boundaries to thedata become evident and cases that fall outside of those boundaries areindicative of either corrupted data or data from a totally unexpectedsituation. It is sometimes desirable for the system designer to addrules to handle these cases. These can be fuzzy logic-based rules orrules based on human intelligence. One example would be that whencertain parts of the data vector fall outside of expected bounds thatthe system defaults to an airbag-enable state or the previouslydetermined state.

2. Genetic algorithms. When developing a neural network algorithm for aparticular vehicle, there is no guarantee that the best of all possiblealgorithms has been selected. One method of improving the probabilitythat the best algorithm has been selected is to incorporate some of theprinciples of genetic algorithms. In one application of this theory, thenetwork architecture and/or the node weights are varied pseudo-randomlyto attempt to find other combinations which have higher success rates.The discussion of such genetic algorithms systems appears in the bookComputational Intelligence referenced above.

Although neural networks are preferred other classifiers such asBayesian classifiers can be used as well as any other patternrecognition system. A key feature of most of the inventions disclosedherein is the recognition that the technology of pattern recognitionrather than deterministic mathematics should be applied to solving theoccupant sensing problem.

6.1 Neural Networks

An occupant can move from a position safely displaced from the airbag toa position where he or she can be seriously injured by the deployment ofan airbag within a fraction of a second during pre-crash braking, forexample. On the other hand, it takes a substantially longer time periodto change the seat occupancy state from a forward facing person to arear facing child seat, or even from a forward facing child seat to arear facing child seat. This fact can be used in the discriminationprocess through post-processing algorithms. One method, which alsoprepares for DOOP, is to use a two-layered neural network or twoseparate neural networks. The first one categorizes the seat occupancyinto, for example, (1) empty seat, (2) rear facing child seat, (3)forward facing child seat and (4) forward facing human (not in a childseat). The second is used for occupant position determination. In theimplementation, the same input layer can be used for both neuralnetworks but separate hidden and output layers are used. This isillustrated in FIG. 53 which is similar to FIG. 19 b with the additionof a post processing operation for both the categorization and positionnetworks and the separate hidden layer nodes for each network.

If the categorization network determines that either a category (3) or(4) exists, then the second network is run, which determines thelocation of the occupant. Significant averaging of the vectors is usedfor the first network and substantial evidence is required before theoccupancy class is changed. For example, if data is acquired every 10milliseconds, the first network might be designed to require 600 out of1000 changed vectors before a change of state is determined. In thiscase, at least 6 seconds of confirming data would be required. Such asystem would therefore not be fooled by a momentary placement of anewspaper by a forward facing human, for example, that might look like arear-facing child seat.

If, on the other hand, a forward facing human were chosen, his or herposition could be determined every 10 milliseconds. A decision that theoccupant had moved out of position would not necessarily be made fromone 10 millisecond reading unless that reading was consistent withprevious readings. Nevertheless, a series of consistent readings wouldlead to a decision within 10 milliseconds of when the occupant crossedover into the danger zone proximate to the airbag module. This method ofusing history is used to eliminate the effects of temperature gradients,for example, or other events that could temporarily distort one or morevectors. The algorithms which perform this analysis are part of thepost-processor.

More particularly, in one embodiment of the method in accordance with atleast one of the inventions herein in which two neural networks are usedin the control of the deployment of an occupant restraint device basedon the position of an object in a passenger compartment of a vehicle,several wave-emitting and receiving transducers are mounted on thevehicle. In one preferred embodiment, the transducers are ultrasonictransducers which simultaneously transmit and receive waves at differentfrequencies from one another. A determination is made by a first neuralnetwork whether the object is of a type requiring deployment of theoccupant restraint device in the event of a crash involving the vehiclebased on the waves received by at least some of the transducers afterbeing modified by passing through the passenger compartment. If so,another determination is made by a second neural network whether theposition of the object relative to the occupant restraint device wouldcause injury to the object upon deployment of the occupant restraintdevice based on the waves received by at least some of the transducers.The first neural network is trained on signals from at least some of thetransducers representative of waves received by the transducers whendifferent objects are situated in the passenger compartment. The secondneural network is trained on signals from at least some of thetransducers when different objects in different positions are situatedin the passenger compartment.

The transducers used in the training of the first and second neuralnetworks and operational use of method are not necessary the sametransducers and different sets of transducers can be used for the typingor categorizing of the object via the first neural network and theposition determination of the object via the second neural network.

The modifications described above with respect to the use of ultrasonictransducers can also be used in conjunction with a dual neural networksystem. For example, motion of a respective vibrating element or cone ofone or more of the transducers may be electronically or mechanicallydiminished or suppressed to reduce ringing of the transducer and/or oneor more of the transducers may be arranged in a respective tube havingan opening through which the waves are transmitted and received.

In another embodiment of the invention, a method for categorizing anddetermining the position of an object in a passenger compartment of avehicle entails mounting a plurality of wave-receiving transducers onthe vehicle, training a first neural network on signals from at leastsome of the transducers representative of waves received by thetransducers when different objects in different positions are situatedin the passenger compartment, and training a second neural network onsignals from at least some of the transducers representative of wavesreceived by the transducers when different objects in differentpositions are situated in the passenger compartment. As such, the firstneural network provides an output signal indicative of thecategorization of the object while the second neural network provides anoutput signal indicative of the position of the object. The transducersmay be controlled to transmit and receive waves each at a differentfrequency, as discussed elsewhere herein, and one or more of thetransducers may be arranged in a respective tube having an openingthrough which the waves are transmitted and received.

Although this system is described with particular advantageous use forultrasonic and optical transducers, it is conceivable that othertransducers other than the ultrasonics or optics can also be used inaccordance with the invention. A dual neural network is a form of amodular neural network and both are subsets of combination neuralnetworks.

The system used in a preferred implementation of at least one of theinventions disclosed herein for the determination of the presence of arear facing child seat, of an occupant or of an empty seat, for example,is the artificial neural network, which is also commonly referred to asa trained neural network. In one case, illustrated in FIG. 1, thenetwork operates on the returned signals as sensed by transducers 6, 8,9 and 10, for example. Through a training session, the system is taughtto differentiate between the different cases. This is done by conductinga large number of experiments where a selection of the possible childseats is placed in a large number of possible orientations on the frontpassenger seat. Similarly, a sufficiently large number of experimentsare run with human occupants and with boxes, bags of groceries and otherobjects (both inanimate and animate). For each experiment with differentobjects and the same object in different positions, the returned signalsfrom the transducers 6, 8, 9 and 10, for example, are associated withthe identification of the occupant in the seat or the empty seat andinformation about the occupant such as its orientation if it is a childseat and/or position. Data sets are formed from the returned signals andthe identification and information about the occupant or the absence ofan occupant. The data sets are input into a neural network-generatingprogram that creates a trained neural network that can, upon receivinginput of returned signals from the transducers 6, 8, 9 and 10, providean output of the identification and information about the occupant mostlikely situated in the seat or ascertained the existence of an emptyseat. Sometimes as many as 1,000,000 such experiments are run before theneural network is sufficiently trained and tested so that it candifferentiate among the several cases and output the correct decisionwith a very high probability. The data from each trial is combined toform a one-dimensional array of data called a vector. Of course, it mustbe realized that a neural network can also be trained to differentiateamong additional cases, for example, a forward facing child seat. It canalso be trained to recognize the existence of one or more boxes or othercargo within a truck trailer, cargo container, automobile trunk orrailroad car, for example.

Considering now FIG. 9, the normalized data from the ultrasonictransducers 6, 8, 9 and 10, the seat track position detecting sensor 74,the reclining angle detecting sensor 57, from the weight sensor(s) 7, 76and 97, from the heartbeat sensor 71, the capacitive sensor 78 and themotion sensor 73 are input to the neural network 65, and the neuralnetwork 65 is then trained on this data. More specifically, the neuralnetwork 65 adds up the normalized data from the ultrasonic transducers,from the seat track position detecting sensor 74, from the recliningangle detecting sensor 57, from the weight sensor(s) 7, 76 and 97, fromthe heartbeat sensor 71, from the capacitive sensor 78 and from themotion sensor 73 with each data point multiplied by an associated weightaccording to the conventional neural network process to determinecorrelation function (step S6 in FIG. 12).

Looking now at FIG. 19B, in this embodiment, 144 data points areappropriately interconnected at 25 connecting points of layer 1, andeach data point is mutually correlated through the neural networktraining and weight determination process. The 144 data points consistof 138 measured data points from the ultrasonic transducers, the data(139th) from the seat track position detecting sensor 74, the data(140th) from the reclining angle detecting sensor 57, the data (141st)from the weight sensor(s) 7 or 76, the data (142^(nd)) from theheartbeat sensor 71, the data (143^(rd)) from the capacitive sensor andthe data (144^(th)) from the motion sensor (the last three inputs arenot shown on FIG. 19B. Each of the connecting points of the layer 1 hasan appropriate threshold value, and if the sum of measured data exceedsthe threshold value, each of the connecting points will output a signalto the connecting points of layer 2. Although the weight sensor input isshown as a single input, in general there will be a separate input fromeach weight sensor used. For example, if the seat has four seat supportsand a strain measuring element is used on each support, what will befour data inputs to the neural network.

The connecting points of the layer 2 comprises 20 points, and the 25connecting points of the layer 1 are appropriately interconnected as theconnecting points of the layer 2. Similarly, each data is mutuallycorrelated through the training process and weight determination asdescribed above and in the above-referenced neural network texts. Eachof the 20 connecting points of the layer 2 has an appropriate thresholdvalue, and if the sum of measured data exceeds the threshold value, eachof the connecting points will output a signal to the connecting pointsof layer 3.

The connecting points of the layer 3 comprises 3 points, and theconnecting points of the layer 2 are interconnected at the connectingpoints of the layer 3 so that each data is mutually correlated asdescribed above. If the sum of the outputs of the connecting points oflayer 2 exceeds a threshold value, the connecting points of the latter 3will output Logic values (100), (010), and (001) respectively, forexample.

The neural network 65 recognizes the seated-state of a passenger A bytraining as described in several books on Neural Networks mentioned inthe above referenced patents and patent applications. Then, aftertraining the seated-state of the passenger A and developing the neuralnetwork weights, the system is tested. The training procedure and thetest procedure of the neural network 65 will hereafter be described witha flowchart shown in FIG. 12.

The threshold value of each connecting point is determined bymultiplying weight coefficients and summing up the results in sequence,and the aforementioned training process is to determine a weightcoefficient Wj so that the threshold value (ai) is a previouslydetermined output.ai=ΣWj•Xj (j=1 to N)wherein

-   -   Wj is the weight coefficient,    -   Xj is the data and    -   N is the number of samples.

Based on this result of the training, the neural network 65 generatesthe weights for the coefficients of the correlation function or thealgorithm (step S7).

At the time the neural network 65 has learned a suitable number ofpatterns of the training data, the result of the training is tested bythe test data. In the case where the rate of correct answers of theseated-state detecting unit based on this test data is unsatisfactory,the neural network is further trained and the test is repeated. In thisembodiment, the test was performed based on about 600,000 test patterns.When the rate of correct test result answers was at about 98%, thetraining was ended. Further improvements to the ultrasonic occupantsensor system has now resulted in accuracies exceeding 98% and for theoptical system exceeding 99%.

The neural network software operates as follows. The training data isused to determine the weights which multiply the values at the variousnodes at the lower level when they are combined at nodes at a higherlevel. Once a sufficient number of iterations have been accomplished,the independent data is used to check the network. If the accuracy ofthe network using the independent data is lower than the last time thatit was checked using the independent data, then the previous weights aresubstituted for the new weights and training of the network continues ona different path. Thus, although the independent data is not used totrain the network, it does strongly affect the weights. It is thereforenot really independent. Also, both the training data and the independentdata are created so that all occupancy states are roughly equallyrepresented. As a result, a third set of data is used which isstructured to more closely represent the real world of vehicleoccupancy. This third data set, the “real world” data, is then used toarrive at a figure as to the real accuracy of the system.

The neural network 65 has outputs 65 a, 65 b and 65 c (FIG. 9). Each ofthe outputs 65 a, 65 b and 65 c outputs a signal of logic 0 or 1 to agate circuit or algorithm 77. Based on the signals from the outputs 65a, 65 b and 65 c, any one of these combination (100), (010) and (001) isobtained. In another preferred embodiment, all data for the empty seatwas removed from the training set and the empty seat case was determinedbased on the output of the weight sensor alone. This simplifies theneural network and improves its accuracy.

In this embodiment, the output (001) correspond to a vacant seat, a seatoccupied by an inanimate object or a seat occupied by a pet (VACANT),the output (010) corresponds to a rear facing child seat (RFCS) or anabnormally seated passenger (ASP or OOPA), and the output (100)corresponds to a normally seated passenger (NSP or FFA) or a forwardfacing child seat (FFCS).

The gate circuit (seated-state evaluation circuit) 77 can be implementedby an electronic circuit or by a computer algorithm by those skilled inthe art and the details will not be presented here. The function of thegate circuit 77 is to remove the ambiguity that sometimes results whenultrasonic sensors and seat position sensors alone are used. Thisambiguity is that it is sometimes difficult to differentiate between arear facing child seat (RFCS) and an abnormally seated passenger (ASP),or between a normally seated passenger (NSP) and a forward facing childseat (FFCS). By the addition of one or more weight sensors in thefunction of acting as a switch when the weight is above or below 60lbs., it has been found that this ambiguity can be eliminated. The gatecircuit therefore takes into account the output of the neural networkand also the weight from the weight sensor(s) as being above or below 60lbs. and thereby separates the two cases just described and results infive discrete outputs.

The use of weight data must be heavily filtered since during drivingconditions, especially on rough roads or during an accident, the weightsensors will give highly varying output. The weight sensors, therefore,are of little value during the period of time leading up to andincluding a crash and their influence must be minimized during this timeperiod. One way of doing this is to average the data over a long periodof time such as from 5 seconds to a minute or more.

Thus, the gate circuit 77 fulfills a role of outputting five kinds ofseated-state evaluation signals, based on a combination of three kindsof evaluation signals from the neural network 65 and superimposedinformation from the weight sensor(s). The five seated-state evaluationsignals are input to an airbag deployment determining circuit that ispart of the airbag system and will not be described here. As disclosedin the above-referenced patents and patent applications, the output ofthis system can also be used to activate a variety of lights or alarmsto indicate to the operator of the vehicle the seated state of thepassenger. The system that has been here described for the passengerside is also applicable for the most part for the driver side.

An alternate and preferred method of accomplishing the functionperformed by the gate circuit is to use a modular neural network. Inthis case, the first level neural network is trained on determiningwhether the seat is occupied or vacant. The input to this neural networkconsists of all of the data points described above. Since the onlyfunction of this neural network is to ascertain occupancy, the accuracyof this neural network is very high. If this neural network determinesthat the seat is not vacant, then the second level neural networkdetermines the occupancy state of the seat.

In this embodiment, although the neural network 65 has been employed asan evaluation circuit, the mapping data of the coefficients of acorrelation function may also be implemented or transferred to amicrocomputer to constitute the evaluation circuit (see Step S8 in FIG.12).

According to the seated-state detecting unit of the present invention,the identification of a vacant seat (VACANT), a rear facing child seat(RFCS), a forward facing child seat (FFCS), a normally seated adultpassenger (NSP), an abnormally seated adult passenger (ASP), can bereliably performed. Based on this identification, it is possible tocontrol a component, system or subsystem in the vehicle. For example, aregulation valve which controls the inflation or deflation of an airbagmay be controlled based on the evaluated identification of the occupantof the seat. This regulation valve may be of the digital or analog type.A digital regulation valve is one that is in either of two states, openor closed. The control of the flow is then accomplished by varying thetime that the valve is open and closed, i.e., the duty cycle.

The neural network has been previously trained on a significant numberof occupants of the passenger compartment. The number of such occupantsdepends strongly on whether the driver or the passenger seat is beinganalyzed. The variety of seating states or occupancies of the passengerseat is vastly greater than that of the driver seat. For the driverseat, a typical training set will consist of approximately 100 differentvehicle occupancies. For the passenger seat, this number can exceed1000. These numbers are used for illustration purposes only and willdiffer significantly from vehicle model to vehicle model. Of course manyvectors of data will be taken for each occupancy as the occupant assumesdifferent positions and postures.

The neural network is now used to determine which of the storedoccupancies most closely corresponds to the measured data. The output ofthe neural network can be an index of the setup that was used duringtraining that most closely matches the current measured state. Thisindex can be used to locate stored information from the matched trainedoccupancy. Information that has been stored for the trained occupancytypically includes the locus of the centers of the chest and head of thedriver, as well as the approximate radius of pixels which is associatedwith this center to define the head area, for example. For the case ofFIG. 8A, it is now known from this exercise where the head, chest, andperhaps the eyes and ears, of the driver are most likely to be locatedand also which pixels should be tracked in order to know the preciseposition of the driver's head and chest. What has been described aboveis the identification process for automobile occupancy and is onlyrepresentative of the general process. A similar procedure, althoughusually simpler with fewer steps, is applicable to other vehiclemonitoring cases.

The use of trainable pattern recognition technologies such as neuralnetworks is an important part of the some of the inventions disclosesherein particularly for the automobile occupancy case, although othernon-trained pattern recognition systems such as fuzzy logic,correlation, Kalman filters, and sensor fusion can also be used. Thesetechnologies are implemented using computer programs to analyze thepatterns of examples to determine the differences between differentcategories of objects. These computer programs are derived using a setof representative data collected during the training phase, called thetraining set. After training, the computer programs output a computeralgorithm containing the rules permitting classification of the objectsof interest based on the data obtained after installation in thevehicle. These rules, in the form of an algorithm, are implemented inthe system that is mounted onto the vehicle. The determination of theserules is important to the pattern recognition techniques used in atleast one of the inventions disclosed herein. Artificial neural networksusing back propagation are thus far the most successful of the ruledetermination approaches, however, research is underway to developsystems with many of the advantages of back propagation neural networks,such as learning by training, without the disadvantages, such as theinability to understand the network and the possibility of notconverging to the best solution. In particular, back propagation neuralnetworks will frequently give an unreasonable response when presentedwith data than is not within the training data. It is well known thatneural networks are good at interpolation but poor at extrapolation. Acombined neural network fuzzy logic system, on the other hand, cansubstantially solve this problem. Additionally, there are many otherneural network systems in addition to back propagation. In fact, onetype of neural network may be optimum for identifying the contents ofthe passenger compartment and another for determining the location ofthe object dynamically.

Numerous books and articles, including more that 500 U.S. patents,describe neural networks in great detail and thus the theory andapplication of this technology is well known and will not be repeatedhere. Except in a few isolated situations where neural networks havebeen used to solve particular problems limited to engine control, forexample, they have not previously been applied to automobiles, trucks orother vehicle monitoring situations.

The system generally used in the instant invention, therefore, for thedetermination of the presence of a rear facing child seat, an occupant,or an empty seat is the artificial neural network or a neural-fuzzysystem. In this case, the network operates on the returned signals froma CCD or CMOS array as sensed by transducers 49, 50, 51 and 54 in FIG.8D, for example. For the case of the front passenger seat, for example,through a training session, the system is taught to differentiatebetween the three cases. This is done by conducting a large number ofexperiments where available child seats are placed in numerous positionsand orientations on the front passenger seat of the vehicle.

Once the network is determined, it is possible to examine the result todetermine, from the algorithm created by the neural network software,the rules that were finally arrived at by the trial and error trainingtechnique. In that case, the rules can then be programmed into amicroprocessor. Alternately, a neural computer can be used to implementthe neural network directly. In either case, the implementation can becarried out by those skilled in the art of pattern recognition usingneural networks. If a microprocessor is used, a memory device is alsorequired to store the data from the analog to digital converters whichdigitize the data from the receiving transducers. On the other hand, ifa neural network computer is used, the analog signal can be fed directlyfrom the transducers to the neural network input nodes and anintermediate memory is not required. Memory of some type is needed tostore the computer programs in the case of the microprocessor system andif the neural computer is used for more than one task, a memory isneeded to store the network specific values associated with each task.

A review of the literature on neural networks yields the conclusion thatthe use of such a large training set is unique in the neural networkfield. The rule of thumb for neural networks is that there must be atleast three training cases for each network weight. Thus, for example,if a neural network has 156 input nodes, 10 first hidden layer nodes, 5second hidden layer nodes, and one output node this results in a totalof 1,622 weights. According to conventional theory 5000 trainingexamples should be sufficient. It is highly unexpected, therefore, thatgreater accuracy would be achieved through 100 times that many cases. Itis thus not obvious and cannot be deduced from the neural networkliterature that the accuracy of the system will improve substantially asthe size of the training database increases even to tens of thousands ofcases. It is also not obvious looking at the plots of the vectorsobtained using ultrasonic transducers that increasing the number oftests or the database size will have such a significant effect on thesystem accuracy. Each of the vectors is typically a rather course plotwith a few significant peaks and valleys. Since the spatial resolutionof an ultrasonic system is typically about 2 to 4 inches, it is onceagain surprising that such a large database is required to achievesignificant accuracy improvements.

The back propagation neural network is a very successful general-purposenetwork. However, for some applications, there are other neural networkarchitectures that can perform better. If it has been found, forexample, that a parallel network as described above results in asignificant improvement in the system, then, it is likely that theparticular neural network architecture chosen has not been successful inretrieving all of the information that is present in the data. In such acase, an RCE, Stochastic, Logicon Projection, cellular, support vectormachine or one of the other approximately 30 types of neural networkarchitectures can be tried to see if the results improve. This parallelnetwork test, therefore, is a valuable tool for determining the degreeto which the current neural network is capable of using efficiently theavailable data.

One of the salient features of neural networks is their ability of findpatterns in data regardless of its source. Neural networks work wellwith data from ultrasonic sensors, optical imagers, strain gage andbladder weight sensors, temperature sensors, chemical sensors, radiationsensors, pressure sensors, electric field sensors, capacitance basedsensors, any other wave sensors including the entire electromagneticspectrum, etc. If data from any sensors can be digitized and fed into aneural network generating program and if there is information in thepattern of the data then neural networks can be a viable method ofidentifying those patterns and correlating them with a desired outputfunction. Note that although the inventions disclosed herein preferablyuse neural networks and combination neural networks to be describednext, these inventions are not limited to this form or method of patternrecognition. The major breakthrough in occupant sensing came with therecognition by the current assignee that ordinary analysis usingmathematical equations where the researcher looks at the data andattempts, based on the principles of statistics, engineering or physics,to derive the relevant relationships between the data and the categoryand location of an occupying item, is not the proper approach and thatpattern recognition technologies should be used. This is believed to bethe first use of such pattern recognition technologies in the automobilesafety and monitoring fields with the exception that neural networkshave been used by the current assignee and others as the basis of acrash sensor algorithm and by certain automobile manufacturers forengine control. Note for many monitoring situations in truck trailers,cargo containers and railroad cars where questions such as “is thereanything in the vehicle?” are asked, neural networks may not always berequired.

7. Other Products, Outputs, Features

Once the occupancy state of the seat (or seats) in the vehicle or of thevehicle itself, as in a cargo container, truck trailer or railroad car,is known, this information can be used to control or affect theoperation of a significant number of vehicular systems, components anddevices. That is, the systems, components and devices in the vehicle canbe controlled and perhaps their operation optimized in consideration ofthe occupancy of the seat(s) in the vehicle or of the vehicle itself.Thus, the vehicle includes control means coupled to the processor meansfor controlling a component or device in the vehicle in consideration ofthe output indicative of the current occupancy state of the seatobtained from the processor means. The component or device can be anairbag system including at least one deployable airbag whereby thedeployment of the airbag is suppressed, for example, if the seat isoccupied by a rear-facing child seat, or otherwise the parameters of thedeployment are controlled. Thus, the seated-state detecting unitdescribed above may be used in a component adjustment system and methoddescribed below when the presence of a human being occupying the seat isdetected. The component can also be a telematics system such as theSkybitz or OnStar systems where information about the occupancy state ofthe vehicle, or changes in that state, can be sent to a remote site.

The component adjustment system and methods in accordance with theinvention can automatically and passively adjust the component based onthe morphology of the occupant of the seat. As noted above, theadjustment system may include the seated-state detecting unit describedabove so that it will be activated if the seated-state detecting unitdetects that an adult or child occupant is seated on the seat, that is,the adjustment system will not operate if the seat is occupied by achild seat, pet or inanimate objects. Obviously, the same system can beused for any seat in the vehicle including the driver seat and thepassenger seat(s). This adjustment system may incorporate the samecomponents as the seated-state detecting unit described above, that is,the same components may constitute a part of both the seated-statedetecting unit and the adjustment system, for example, the weightmeasuring system.

The adjustment system described herein, although improved over the priorart, will at best be approximate since two people, even if they areidentical in all other respects, may have a different preferred drivingposition or other preferred adjusted component location or orientation.A system that automatically adjusts the component, therefore, shouldlearn from its errors. Thus, when a new occupant sits in the vehicle,for example, the system automatically estimates the best location of thecomponent for that occupant and moves the component to that location,assuming it is not already at the best location. If the occupant changesthe location, the system should remember that change and incorporate itinto the adjustment the next time that person enters the vehicle and isseated in the same seat. Therefore, the system need not make a perfectselection the first time but it should remember the person and theposition the component was in for that person. The system, therefore,makes one, two or three measurements of morphological characteristics ofthe occupant and then adjusts the component based on an algorithm. Theoccupant will correct the adjustment and the next time that the systemmeasures the same measurements for those measurement characteristics, itwill set the component to the corrected position. As such, preferredcomponents for which the system in accordance with the invention is mostuseful are those which affect a driver of the vehicle and relate to thesensory abilities of the driver, i.e., the mirrors, the seat, thesteering wheel and steering column and accelerator, clutch and brakepedals.

Thus, although the above description mentions that the airbag system canbe controlled by the control circuitry 20 (FIG. 1), any vehicularsystem, component or subsystem can be controlled based on theinformation or data obtained by transmitter and/or receiver assemblies6, 8, 9 and 10. Control circuitry 20 can be programmed or trained, iffor example a neural network is used, to control heating anair-conditioning systems based on the presence of occupants in certainpositions so as to optimize the climate control in the vehicle. Theentertainment system can also be controlled to provide sound only tolocations at which occupants are situated. There is no limit to thenumber and type of vehicular systems, components and subsystems that canbe controlled using the analysis techniques described herein.

Furthermore, if multiple vehicular systems are to be controlled bycontrol circuitry 20, then these systems can be controlled by thecontrol circuitry 20 based on the status of particular components of thevehicle. For example, an indication of whether a key is in the ignitioncan be used to direct the control circuitry 20 to either control anairbag system (when the key is present in the ignition) or an antitheftsystem (when the key is not present in the ignition). Control circuitry20 would thus be responsive to the status of the ignition of the motorvehicle to perform one of a plurality of different functions. Moreparticularly, the pattern recognition algorithm, such as the neuralnetwork described herein, could itself be designed to perform in adifferent way depending on the status of a vehicular component such asthe detected presence of a key in the ignition. It could provide oneoutput to control an antitheft system when a key is not present andanother output when a key is present using the same inputs from thetransmitter and/or receiver assemblies 6, 8, 9 and 10.

The algorithm in control circuitry 20 can also be designed to determinethe location of the occupant's eyes either directly or indirectlythrough a determination of the location of the occupant and anestimation of the position of the eyes therefrom. As such, the positionof the rear view mirror 55 can be adjusted to optimize the driver's usethereof.

7.1 Control of Passive Restraints

The use of the vehicle interior monitoring system to control thedeployment of an airbag is discussed in detail in U.S. Pat. No.5,653,462 referenced above. In that case, the control is based on theuse of a pattern recognition system, such as a neural network, todifferentiate between the occupant and his extremities in order toprovide an accurate determination of the position of the occupantrelative to the airbag. If the occupant is sufficiently close to theairbag module that he is more likely to be injured by the deploymentitself than by the accident, the deployment of the airbag is suppressed.This process is carried further by the interior monitoring systemdescribed herein in that the nature or identity of the object occupyingthe vehicle seat is used to contribute to the airbag deploymentdecision. FIG. 4 shows a side view illustrating schematically theinterface between the vehicle interior monitoring system of at least oneof the inventions disclosed herein and the vehicle airbag system 44. Asimilar system can be provided for the passenger as described in U.S.patent application Ser. No. 10/151,615 filed May 20, 2002.

In this embodiment, ultrasonic transducers 8 and 9 transmit bursts ofultrasonic waves that travel to the occupant where they are reflectedback to transducers or receptors/receivers 8 and 9. The time periodrequired for the waves to travel from the generator and return is usedto determine the distance from the occupant to the airbag as describedin the aforementioned U.S. Pat. No. 5,653,462, i.e., and thus may alsobe used to determine the position or location of the occupant. Anoptical imager based system would also be appropriate. In the invention,however, the portion of the return signal that represents the occupants'head or chest, has been determined based on pattern recognitiontechniques such as a neural network. The relative velocity of theoccupant toward the airbag can then be determined, by Doppler principlesor from successive position measurements, which permits a sufficientlyaccurate prediction of the time when the occupant would become proximateto the airbag. By comparing the occupant relative velocity to theintegral of the crash deceleration pulse, a determination as to whetherthe occupant is being restrained by a seatbelt can also be made whichthen can affect the airbag deployment initiation decision. Alternately,the mere knowledge that the occupant has moved a distance that would notbe possible if he were wearing a seatbelt gives information that he isnot wearing one.

Another method of providing a significant improvement to the problem ofdetermining the position of the occupant during vehicle deceleration isto input the vehicle deceleration directly into the occupant sensingsystem. This can be done through the use of the airbag crash sensoraccelerometer or a dedicated accelerometer can be used. Thisdeceleration or its integral can be entered directly into the neuralnetwork or can be integrated through an additional post-processingalgorithm. Post processing in general is discussed in section 11.7 ofthe parent '881 application. One significant advantage of neuralnetworks is their ability to efficiently use information from anysource. It is the ultimate “sensor fusion” system.

A more detailed discussion of this process and of the advantages of thevarious technologies, such as acoustic or electromagnetic, can be foundin SAE paper 940527, “Vehicle Occupant Position Sensing” by Breed etal., In this paper, it is demonstrated that the time delay required foracoustic waves to travel to the occupant and return does not prevent theuse of acoustics for position measurement of occupants during the crashevent. For position measurement and for many pattern recognitionapplications, ultrasonics is the preferred technology due to the lack ofadverse health effects and the low cost of ultrasonic systems comparedwith either camera, laser or radar based systems. This situation haschanged, however, as the cost of imagers has come down. The mainlimiting feature of ultrasonics is the wavelength, which places alimitation on the size of features that can be discerned. Opticalsystems, for example, are required when the identification of particularindividuals is desired.

FIG. 26 is a schematic drawing of one embodiment of an occupantrestraint device control system in accordance with the invention. Thefirst step is to obtain information about the contents of the seat atstep 338, when such contents are present on the seat. To this end, apresence sensor can be employed to activate the system only when thepresence of an object, or living being, is detected. Next, at step 339,a signal is generated based on the contents of the seat, with differentsignals being generated for different contents of the seat. Thus, whilea signal for a dog will be different than the signal for a child set,the signals for different child seats will not be that different. Next,at step 340, the signal is analyzed to determine whether a child seat ispresent, whether a child seat in a particular orientation is presentand/or whether a child seat in a particular position is present.Deployment control 341 provides a deployment control signal or commandbased on the analysis of the signal generated based on the contents ofthe seat. This signal or command is directed to the occupant protectionor restraint device 342 to provide for deployment for that particularcontent of the seat. The system continually obtains information aboutthe contents of the seat until such time as a deployment signal isreceived from, e.g., a crash sensor, to initiate deployment of theoccupant restraint device.

FIG. 27 is a flow chart of the operation of one embodiment of anoccupant restraint device control method in accordance with theinvention. The first step is to determine whether contents are presenton the seat at step 910. If so, information is obtained about thecontents of the seat at step 344. At step 345, a signal is generatedbased on the contents of the seat, with different signals beinggenerated for different contents of the seat. The signal is analyzed todetermine whether a child seat is present at step 346, whether a childseat in a particular orientation is present at step 347 and/or whether achild seat in a particular position is present at step 348. Deploymentcontrol 349 provides a deployment control signal or command based on theanalysis of the signal generated based on the contents of the seat. Thissignal or command is directed to the occupant protection or restraintdevice 350 to provide for deployment for those particular contents ofthe seat. The system continually obtains information about the contentsof the seat until such time as a deployment signal is received from,e.g., a crash sensor 351, to initiate deployment of the occupantrestraint device.

In another implementation, the sensor algorithm may determine the ratethat gas is generated to affect the rate that the airbag is inflated. Inall of these cases, the position of the occupant is used to affect thedeployment of the airbag either as to whether or not it should bedeployed at all, the time of deployment and/or the rate of inflationand/or deflation.

Such a system can also be used to positively identify or confirm thepresence of a rear facing child seat in the vehicle, if the child seatis equipped with a resonator. In this case, a resonator 18 is placed onthe forward most portion of the child seat, or in some other convenientposition, as shown in FIG. 1. The resonator 18, or other type of signalgenerating device, such as an RFID tag, which generates a signal uponexcitation, e.g., by a transmitted energy signal, can be used not onlyto determine the orientation of the child seat but also to determine theposition of the child seat (in essentially the same manner as describedabove with respect to determining the position of the seat and theposition of the seatbelt).

The determination of the presence of a child seat can be used to affectanother system in the vehicle. Most importantly, deployment of anoccupant restraint device can be controlled depending on whether a childseat is present. Control of the occupant restraint device may entailsuppression of deployment of the device. If the occupant restraintdevice is an airbag, e.g., a frontal airbag or a side airbag, control ofthe airbag deployment may entail not only suppression of the deploymentbut also depowered deployment, adjustment of the orientation of theairbag, adjustment of the inflation rate or inflation time and/oradjustment of the deflation rate or time.

Several systems are in development for determining the location of anoccupant and modifying the deployment of the airbag based of his or herposition. These systems are called “smart airbags”. The passive seatcontrol system in accordance with at least one of the inventionsdisclosed herein can also be used for this purpose as illustrated inFIG. 28. This figure shows an inflated airbag 352 and an arrangement forcontrolling both the flow of gas into and out of the airbag during acrash. The determination is made based on height sensors 353, 354 and355 (FIG. 25) located in the headrest, a weight sensor 252 in the seatand the location of the seat which is known by control circuit 254.Other smart airbags systems rely only on the position of the occupantdetermined from various position sensors using ultrasonics or opticalsensors, or equivalent.

The weight sensor coupled with the height sensor and the occupant'svelocity relative to the vehicle, as determined by the occupant positionsensors, provides information as to the amount of energy that the airbagwill need to absorb during the impact of the occupant with the airbag.This, along with the location of the occupant relative to the airbag, isthen used to determine the amount of gas that is to be injected into theairbag during deployment and the size of the exit orifices that controlthe rate of energy dissipation as the occupant is interacting with theairbag during the crash. For example, if an occupant is particularlyheavy then it is desirable to increase the amount of gas, and thus theinitial pressure, in the airbag to accommodate the larger force whichwill be required to arrest the relative motion of the occupant. Also,the size of the exit orifices should be reduced, since there will be alarger pressure tending to force the gas out of the orifices, in orderto prevent the bag from bottoming out before the occupant's relativevelocity is arrested. Similarly, for a small occupant the initialpressure would be reduced and the size of the exit orifices increased.If, on the other hand, the occupant is already close to the airbag thenthe amount of gas injected into the airbag will need to be reduced.

With further reference to FIG. 28, another and preferred approach is toincorporate an accelerometer 362, 363 into the seatbelt or the airbagsurface, respectively, and to measure the deceleration of the occupant361 and to control the outflow of gas from the airbag 352 to maintainthe occupant's chest acceleration below some maximum value such as 40Gs. This maximum value can be set based on the forecasted severity ofthe crash. If the occupant is wearing a seatbelt, the outflow from theairbag 352 can be significantly reduced since the seatbelt is taking upmost of the load and the airbag 352 then should be used to help spreadthe load over more of the occupant's chest. A sensor 364 which sensespressure in the airbag 352 (see FIG. 28A) can be used since pressure inthe airbag 352 is easily correlated to deceleration of the occupant 361once the occupant 361 has impacted the airbag 352. Although the pressurein the airbag 352 is one indication of the deceleration being impartedto the occupant, or can be used to detect deceleration of the airbag352, and thus contact between the airbag 352 and the occupant 361whereby the deceleration of the airbag 352 after contact is easilycorrelated to the deceleration of the occupant, it is a relatively crudemeasure since it does not take into account the mass of the occupant.Since it is acceleration that should be controlled, it is better tomeasure acceleration rather than pressure in the airbag 352.

Control of the outflow from the airbag 352 is via the control module orcontrol circuit 254 described above, which may be common for all of theembodiments disclosed herein. Control module 254 receives the data fromaccelerometers 362, 363 and based thereon, determines how to control thecontinued inflation of the airbag 352. As appreciated by those skilledin the art, a change in acceleration can be correlated to contactbetween the airbag 352 and the occupant. Any known devices can be usedto control outflow of gas from the airbag 352, including an exit controlvalve or vent 359.

As to forecasting the severity of a crash, anticipatory crash sensorsbased on pattern recognition technology are disclosed in several ofassignee's patents and pending patent applications. The technology nowexists based on research by the assignee to permit the identificationand relative velocity determination to be made for virtually anyairbag-required accident prior to the accident occurring. Thisachievement now allows airbags to be reliably deployed prior to theaccident. The implications of this are significant. Prior to thisachievement, the airbag system had to wait until an accident startedbefore a determination could be made whether to deploy one or more ofthe airbags. The result is that the occupants, especially if unbelted,would frequently achieve a significant velocity relative to the vehiclepassenger compartment before the airbags began to interact with theoccupant and reduce his or her relative velocity. This would frequentlysubject the occupant to high accelerations, in some cases in excess of40 Gs, and in many cases resulted in serious injury or death to theoccupant especially if he or she is unrestrained by a seatbelt orairbag. On the other hand, a vehicle typically undergoes less than amaximum of 20 Gs during even the most severe crashes. Most occupants canwithstand 20 Gs with little or no injury. Thus, as taught herein, if theaccident severity is forecast prior to impact and the outflow of gasfrom the airbag controlled based on the forecast severity, the occupantcan be safely brought to a stationary state during the course of theaccident.

One scenario to forecast the severity of a crash is to use a camera, orradar-based or terahertz-based anticipatory sensor to estimate velocityand profile of impacting object. From the profile or image, anidentification of the class of impacting object can be made and adetermination made of where the object will likely strike the vehicle.Knowing the stiffness of the engagement part of the vehicle allows acalculation of the mass of the impacting object based on an assumptionof the stiffness impacting object. Since the impacting velocity is knownand the acceleration of the vehicle can be determined, we know theimpacting mass and therefore we know the severity or ultimate velocitychange of the accident. From this, the average chest acceleration thatcan be used to just bring the occupant to the velocity of the passengercompartment during the crash can be calculated and therefore theparameters of the airbag system can be set to provide that optimum chestacceleration. By putting the accelerometer 363 on the surface of theairbag 352 that contacts the occupant 361, the actual chest accelerationcan be measured and the size of an exit control valve or vent 359 whichcontrols outflow of gas from the airbag 352 can be adjusted to maintainthe calculated optimum value. With this system, neither crush zone oroccupant sensors are required, thus simplifying and reducing the cost ofthe system and providing optimum results even without initiating theairbag prior to the start of the crash.

Instead of incorporating or otherwise arranging an accelerometer 363into or on the airbag surface, or a pressure sensor which measurespressure in the airbag 352, it is possible to use a similar device whichmeasures acceleration of the airbag surface which comes into contactwith the occupant 361 during deployment. Examples of such devicesinclude a switch, and an optical system for measuring the surfacevelocity either from a position within the airbag 352 or a positionoutside of the airbag 352.

The techniques described immediately above enable a dynamicdetermination of the movement of the occupant after contact with thedeploying airbag based on measurement of a property of the airbag, e.g.,measurement of the pressure in the airbag and measurement of theacceleration of the surface of the airbag contacting the occupant.Movement of the occupant, and specifically acceleration of the occupant,is used to control outflow of gas from the airbag, although it may alsobe used for other purposes. Another technique to provide for dynamicdetermination of the movement of the occupant during deployment of anairbag is illustrated in FIG. 49 wherein an airbag 410 includes tethers412 to or on which sensors 414 are arranged and measure a property ofthe tethers 412. For example, the sensors 414 may be tension sensorswhich measure tension of the tethers 412. Thus, during deployment of theairbag 410, the tethers 412 stretch and by measuring the tension in thetethers 412 via sensors 414, it can be determined when the airbag 410has contacted the occupant and stopped its forward movement.Specifically, since tension is present in the tethers 412 during theoutward movement of the airbag 410 from its housing into contact withthe occupant, the tension readings in the airbag 410 would likely show asharp decrease once the airbag 410 has contacted the occupant andstopped moving toward the occupant as a result. Indeed, a measurement ofthe tension is not absolutely required but rather a determination of areduction in tension above a threshold, or a determination of theabsence of tension, may be all that is required to determine contactwith the occupant. In any case, knowledge of the tension and/or itsvariations can be correlated to the movement of the airbag which in turncorrelates to the movement of the occupant.

Sensors 414 communicate with a control module 416, which may the same asany of the control module or unit disclosed herein. This may be a wiredor wireless communication. Control module 416 communicates with an exitcontrol valve or vent 418 on the airbag 410 and controls outflow of gasfrom the airbag 410 based on the tension measured by the sensors 414,i.e., directs adjustment of the size of the exit control valve 418 toprovide for the desired outflow of gas from the airbag 410 as determinedby the control module 416.

This technique can be applied to any type and form of airbag, includingdriver side airbags, passenger side airbags, side curtain airbags, aswell as to multi-compartment airbags. Tethers can be arranged betweenany opposed inner surfaces which will be forced apart from one anotherduring airbag deployment. Tethers 412 can be made of plastic film oranother material.

There are many ways of varying the amount of gas injected into theairbag some of which are covered in the patent literature and include,for example, inflators where the amount of gas generated and the rate ofgeneration is controllable. For example, in a particular hybrid inflatoronce manufactured by the Allied Signal Corporation, two pyrotechniccharges are available to heat the stored gas in the inflator. Either orboth of the pyrotechnic charges can be ignited and the timing betweenthe ignitions can be controlled to significantly vary the rate of gasflow to the airbag.

The flow of gas out of the airbag is traditionally done through fixeddiameter orifices placed in the bag fabric. Some attempts have been madeto provide a measure of control through such measures as blowout patchesapplied to the exterior of the airbag. Other systems were disclosed inU.S. patent application Ser. No. 07/541,464 filed Feb. 9, 1989, nowabandoned.

FIG. 28A illustrates schematically an inflator 357 generating gas tofill airbag 352 through control valve 358. If the control valve 358 isclosed while a pyrotechnic generator is operating, provision must bemade to store or dump the gas being generated so to prevent the inflatorfrom failing from excess pressure. The flow of gas out of airbag 352 iscontrolled by exit control valve 359. The exit valve 359 can beimplemented in many different ways including, for example, a motoroperated valve located adjacent the inflator and in fluid communicationwith the airbag or a digital flow control valve as discussed elsewhereherein. When control circuit 254 (of any of the embodiments disclosedherein) determines the size and weight of the occupant, the seatposition and the relative velocity of the occupant, it then determinesthe appropriate opening for the exit valve 359, which is coupled to thecontrol circuit 254. A signal is then sent from control circuit 254 tothe motor controlling this valve which provides the proper opening.Alternatively, the airbag includes a gas exit passage 369 having acontrollable and variable size.

Consider, for example, the case of a vehicle that impacts with a pole orbrush in front of a barrier. The crash sensor system may deduce thatthis is a low velocity crash and only initiate the first inflatorcharge. Then as the occupant is moving close to the airbag the barrieris struck but it may now be too late to get the benefit of the secondcharge. For this case, a better solution might be to always generate themaximum amount of gas but to store the excess in a supplemental chamberuntil it is needed.

In a like manner, other parameters can also be adjusted, such as thedirection of the airbag, by properly positioning the angle and locationof the steering wheel relative to the driver. If seatbelt pretensionersare used, the amount of tension in the seatbelt or the force at whichthe seatbelt spools out, for the case of force limiters, could also beadjusted based on the occupant morphological characteristics determinedby the system of at least one of the inventions disclosed herein. Theforce measured on the seatbelt, if the vehicle deceleration is known,gives a confirmation of the mass of the occupant. This force measurementcan also be used to control the chest acceleration given to the occupantto minimize injuries caused by the seatbelt. Naturally, as discussedabove, it is better to measure the acceleration of the chest directly.

In the embodiment shown in FIG. 8A, transmitter/receiver assemblies 49,50, 51 and 54 emit infrared waves that reflect off of the head and chestof the driver and return thereto. Periodically, the device, as commandedby control circuitry 20, transmits a pulse of infrared waves and thereflected signal is detected by the same (i.e. the LEDs and imager arein the same housing) or a different device. The transmitters can eithertransmit simultaneously or sequentially. An associated electroniccircuit and algorithm in control circuitry 20 processes the returnedsignals as discussed above and determines the location of the occupantin the passenger compartment. This information is then sent to the crashsensor and diagnostic circuitry, which may also be resident in controlcircuitry 20 (programmed within a control module), which determines ifthe occupant is close enough to the airbag that a deployment might, byitself, cause injury which exceeds that which might be caused by theaccident itself. In such a case, the circuit disables the airbag systemand thereby prevents its deployment.

In an alternate case, the sensor algorithm assesses the probability thata crash requiring an airbag is in process and waits until thatprobability exceeds an amount that is dependent on the position of theoccupant. Thus, for example, the sensor might decide to deploy theairbag based on a need probability assessment of 50%, if the decisionmust be made immediately for an occupant approaching the airbag, butmight wait until the probability rises above 95% for a more distantoccupant. In the alternative, the crash sensor and diagnostic circuitryoptionally resident in control circuitry 20 may tailor the parameters ofthe deployment (time to initiation of deployment, rate of inflation,rate of deflation, deployment time, etc.) based on the current positionand possibly velocity of the occupant, for example a depowereddeployment.

In another implementation, the sensor algorithm may determine the ratethat gas is generated to affect the rate that the airbag is inflated.One method of controlling the gas generation rate is to control thepressure in the inflator combustion chamber. The higher the internalpressure the faster gas is generated. Once a method of controlling thegas combustion pressure is implemented, the capability exists tosignificantly reduce the variation in inflator properties withtemperature. At lower temperatures the pressure control system wouldincrease the pressure in the combustion chamber and at higher ambienttemperatures it would reduce the pressure. In all of these cases, theposition of the occupant can be used to affect the deployment of theairbag as to whether or not it should be deployed at all, the time ofdeployment and/or the rate of inflation.

The applications described herein have been illustrated using the driverand sometimes the passenger of the vehicle. The same systems ofdetermining the position of the occupant relative to the airbag apply toa driver, front and rear seated passengers, sometimes requiring minormodifications. It is likely that the sensor required triggering timebased on the position of the occupant will be different for the driverthan for the passenger. Current systems are based primarily on thedriver with the result that the probability of injury to the passengeris necessarily increased either by deploying the airbag too late or byfailing to deploy the airbag when the position of the driver would notwarrant it but the passenger's position would. With the use of occupantposition sensors for the passenger and driver, the airbag system can beindividually optimized for each occupant and result in furthersignificant injury reduction. In particular, either the driver orpassenger system can be disabled if either the driver or passenger isout-of-position or if the passenger seat is unoccupied.

There is almost always a driver present in vehicles that are involved inaccidents where an airbag is needed. Only about 30% of these vehicles,however, have a passenger. If the passenger is not present, there isusually no need to deploy the passenger side airbag. The occupantmonitoring system, when used for the passenger side with proper patternrecognition circuitry, can also ascertain whether or not the seat isoccupied, and if not, can disable the deployment of the passenger sideairbag and thereby save the cost of its replacement. The same strategyapplies also for monitoring the rear seat of the vehicle. Also, atrainable pattern recognition system, as used herein, can distinguishbetween an occupant and a bag of groceries, for example. Finally, therehas been much written about the out-of-position child who is standing orotherwise positioned adjacent to the airbag, perhaps due to pre-crashbraking. The occupant position sensor described herein can prevent thedeployment of the airbag in this situation as well as in the situationof a rear facing child seat as described above.

Naturally as discussed elsewhere herein, occupant sensors can also beused for monitoring the rear seats of the vehicle for the purpose, amongothers, of controlling airbag or other restraint deployment.

7.2 Seat, Seatbelt, Steering Wheel and Pedal Adjustment

Let us now consider the adjustment of a seat to adapt to an occupant.First some measurements of the morphological properties of the occupantare necessary. The first characteristic considered is a measurement ofthe height of the occupant from the vehicle seat. This can be done by asensor in the ceiling of the vehicle but this becomes difficult since,even for the same seat location, the head of the occupant will not be atthe same angle with respect to the seat and therefore the angle to aceiling mounted sensor is in general unknown at least as long as onlyone ceiling mounted sensor is used. This problem can be solved if two orthree sensors are used as described in more detail below. The simplestimplementation is to place the sensor in the seat. In U.S. Pat. No.5,694,320, a rear impact occupant protection apparatus is disclosedwhich uses sensors mounted within the headrest. This same system canalso be used to measure the height of the occupant from the seat andthus, for no additional cost assuming the rear impact occupantprotection system described in the '320 patent is provided, the firstmeasure of the occupant's morphology can be achieved. See also FIGS. 24and 25. For some applications, this may be sufficient since it isunlikely that two operators will use the vehicle that both have the sameheight. For other implementations, one or more additional measurementsare used. Naturally, a face, fingerprint, voiceprint or iris recognitionsystem will have the least problem identifying a previous occupant.

Referring now to FIG. 24, an automatic adjustment system for adjusting aseat (which is being used only as an example of a vehicle component) isshown generally at 371 with a movable headrest 356 and ultrasonicsensors 353, 354 and 355 for measuring the height of the occupant of theseat. Other types of wave, energy or radiation receiving sensors mayalso be used in the invention instead of the ultrasonictransmitter/receiver set 353, 354, 355. Power means such as motors 371,372, and 373 connected to the seat for moving the base of the seat,control means such as a control circuit, system or module 254 connectedto the motors and a headrest actuation mechanism using servomotors 374and 375, which may be servomotors, are also illustrated. The seat 4 andheadrest 356 are shown in phantom. Vertical motion of the headrest 356is accomplished when a signal is sent from control module 254 toservomotor 374 through a wire 376. Servomotor 374 rotates lead screw 377which engages with a threaded hole in member 378 causing it to move upor down depending on the direction of rotation of the lead screw 377.Headrest support rods 379 and 380 are attached to member 378 and causethe headrest 356 to translate up or down with member 378. In thismanner, the vertical position of the headrest can be controlled asdepicted by arrow A-A. Ultrasonic transmitters and receivers 353, 354,355 may be replaced by other appropriate wave-generating and receivingdevices, such as electromagnetic, active infrared transmitters andreceivers, and capacitance sensors and electric field sensors.

Wire 381 leads from control module 254 to servomotor 375 which rotateslead screw 382. Lead screw 382 engages with a threaded hole in shaft 383which is attached to supporting structures within the seat shown inphantom. The rotation of lead screw 382 rotates servo motor support 384,upon which servomotor 374 is situated, which in turn rotates headrestsupport rods 379 and 380 in slots 385 and 386 in the seat 4. Rotation ofthe servomotor support 384 is facilitated by a rod 387 upon which theservo motor support 384 is positioned. In this manner, the headrest 356is caused to move in the fore and aft direction as depicted by arrowB-B. Naturally there are other designs which accomplish the same effectin moving the headrest up and down and fore and aft.

The operation of the system is as follows. When an adult or childoccupant is seated on a seat containing the headrest and control systemdescribed above as determined by the neural network 65, the ultrasonictransmitters 353, 354 and 355 emit ultrasonic energy which reflects offof the head of the occupant and is received by the same transducers. Anelectronic circuit in control module 254 contains a microprocessor whichdetermines the distance from the head of the occupant based on the timebetween the transmission and reception of the ultrasonic pulses. In theembodiment wherein capacitance or electric field sensors are usedinstead of ultrasonic transducers, the manner in which the distance canbe determined using such sensors is known to those skilled in the art.

Control module 254 may be within the same microprocessor as neuralnetwork 65 or separate therefrom. The headrest 356 moves up and downuntil it finds the top of the head and then the vertical positionclosest to the head of the occupant and then remains at that position.Based on the time delay between transmission and reception of anultrasonic pulse, the system can also determine the longitudinaldistance from the headrest to the occupant's head. Since the head maynot be located precisely in line with the ultrasonic sensors, or theoccupant may be wearing a hat, coat with a high collar, or may have alarge hairdo, there may be some error in this longitudinal measurement.

When an occupant sits on seat 4, the headrest 356 moves to find the topof the occupant's head as discussed above. This is accomplished using analgorithm and a microprocessor which is part of control circuit 254. Theheadrest 356 then moves to the optimum location for rear impactprotection as described in the above referenced '320 patent. Once theheight of the occupant has been measured, another algorithm in themicroprocessor in control circuit 254 compares the occupant's measuredheight with a table representing the population as a whole and from thistable, the appropriate positions for the seat corresponding to theoccupant's height is selected. For example, if the occupant measured 33inches from the top of the seat bottom, this might correspond to an 85%human, depending on the particular seat and statistical table of humanmeasurements.

Careful study of each particular vehicle model provides the data for thetable of the location of the seat to properly position the eyes of theoccupant within the “eye-ellipse”, the steering wheel within acomfortable reach of the occupant's hands and the pedals within acomfortable reach of the occupant's feet, based on his or her size, etc.Of course one or more pedals can be manually adjusted providing they areprovided with an actuator such as an electric motor and any suchadjustment, either manual or automatic, is contemplated by theinventions disclosed herein.

Once the proper position has been determined by control circuit 254,signals are sent to motors 371, 372, and 373 to move the seat to thatposition, if such movement is necessary. That is, it is possible thatthe seat will be in the proper position so that movement of the seat isnot required. As such, the position of the motors 371,372,373 and/or theposition of the seat prior to occupancy by the occupant may be stored inmemory so that after occupancy by the occupant and determination of thedesired position of the seat, a comparison is made to determine whetherthe desired position of the seat deviates from the current position ofthe seat. If not, movement of the seat is not required. Otherwise, thesignals are sent by the control circuit 254 to the motors. In this case,control circuit 254 would encompass a seat controller.

Instead of adjusting the seat to position the driver in an optimumdriving position, or for use when adjusting the seat of a passenger, itis possible to perform the adjustment with a view toward optimizing theactuation or deployment of an occupant protection or restraint device.For example, after obtaining one or more morphological characteristicsof the occupant, the processor can analyze them and determine one ormore preferred positions of the seat, with the position of the seatbeing related to the position of the occupant, so that if the occupantprotection device is deployed, the occupant will be in an advantageousposition to be protected against injury by such deployment. In this casethen, the seat is adjusted based on the morphology of the occupant viewa view toward optimizing deployment of the occupant protection device.The processor is provided in a training or programming stage with thepreferred seat positions for different morphologies of occupants.

Movement of the seat can take place either immediately upon the occupantsitting in the seat or immediately prior to a crash requiring deploymentof the occupant protection device. In the latter case, if ananticipatory sensing arrangement is used, the seat can be positionedimmediately prior to the impact, much in a similar manner as theheadrest is adjusted for a rear impact as disclosed in the '320 patentreferenced above.

If during some set time period after the seat has been positioned, theoperator changes these adjustments, the new positions of the seat arestored in association with an occupant height class in a second tablewithin control circuit 254. When the occupant again occupies the seatand his or her height has once again been determined, the controlcircuit 254 will find an entry in the second table which takesprecedence over the basic, original table and the seat returns to theadjusted position. When the occupant leaves the vehicle, or even whenthe engine is shut off and the door opened, the seat can be returned toa neutral position which provides for easy entry and exit from thevehicle.

The seat 4 also contains two control switch assemblies 388 and 389 formanually controlling the position of the seat 4 and headrest 356. Theseat control switches 388 permits the occupant to adjust the position ofthe seat if he or she is dissatisfied with the position selected by thealgorithm. The headrest control switches 389 permit the occupant toadjust the position of the headrest in the event that the calculatedposition is uncomfortably close to or far from the occupant's head. Awoman with a large hairdo might find that the headrest automaticallyadjusts so as to contact her hairdo. This adjustment she might findannoying and could then position the headrest further from her head. Forthose vehicles which have a seat memory system for associating the seatposition with a particular occupant, which has been assumed above, theposition of the headrest relative to the occupant's head could also berecorded. Later, when the occupant enters the vehicle, and the seatautomatically adjusts to the recorded preference, the headrest willsimilarly automatically adjust as diagrammed in FIGS. 29A and 29B.

The height of the occupant, although probably the best initialmorphological characteristic, may not be sufficient especially fordistinguishing one driver from another when they are approximately thesame height. A second characteristic, the occupant's weight, can also bereadily determined from sensors mounted within the seat in a variety ofways as shown in FIG. 18 which is a perspective view of the seat shownin FIG. 24 with a displacement or weight sensor 159 shown mounted ontothe seat.

Displacement sensor 159 is supported from supports 165. In general,displacement sensor 164, or another non-displacement sensor, measures aphysical state of a component affected by the occupancy of the seat. Anoccupying item of the seat will cause a force to be exerted downward andthe magnitude of this force is representative of the weight of theoccupying item. Thus, by measuring this force, information about theweight of the occupying item can be obtained. A physical state may beany force changed by the occupancy of the seat and which is reflected inthe component, e.g., strain of a component, compression of a component,tension of a component. Naturally other weight measuring systems asdescribed herein and elsewhere including bladders and strain gages canbe used.

An alternative approach is to measure the load on the vehicle suspensionsystem while the vehicle is at rest (static) or when it is in motion(dynamic). The normal empty state of the vehicle can be determined whenthe vehicle is at rest for a prolonged time period. After then thenumber and location of occupying items can be determined by measuringthe increased load on the suspension devices that attach the vehiclebody to its frame. SAW strain measuring elements can be placed on eachsuspension spring, for example, and used to measure the increased loadon the vehicle as an object or occupant is placed in the vehicle. Thisapproach has the advantage that it is not affected by seatbelt loadings,for example. If the vehicle is monitored as each item is paced in thevehicle a characterization of that item can be made. The taking on offuel, for example, will correspond to a particular loading pattern overtime that will permit the identification of the amount of the weight onthe suspension that can be attributed to fuel. Dynamic measuring systemsare similar to those used in section 6.3 of the parent '881 applicationand thus will not be repeated here.

The system described above is based on the assumption that the occupantwill be satisfied with one seat position throughout an extended drivingtrip. Studies have shown that for extended travel periods that thecomfort of the driver can be improved through variations in the seatposition. This variability can be handled in several ways. For example,the amount and type of variation preferred by an occupant of theparticular morphology can be determined through case studies and focusgroups. If it is found, for example, that the 50 percentile male driverprefers the seat back angle to vary by 5 degrees sinusodially with aone-hour period, this can be programmed to the system. Since the systemknows the morphology of the driver it can decide from a lookup tablewhat is the best variability for the average driver of that morphology.The driver then can select from several preferred possibilities if, forexample, he or she wishes to have the seat back not move at all orfollow an excursion of 10 degrees over two hours.

This system provides an identification of the driver based on twomorphological characteristics which is adequate for most cases. Asadditional features of the vehicle interior identification andmonitoring system described in the above referenced patent applicationsare implemented, it will be possible to obtain additional morphologicalmeasurements of the driver which will provide even greater accuracy indriver identification. Such additional measurements include iris scans,voice prints, face recognition, fingerprints, voiceprints hand or palmprints etc. Two characteristics may not be sufficient to rely on fortheft and security purposes, however, many other driver preferences canstill be added to seat position with this level of occupant recognitionaccuracy. These include the automatic selection of a preferred radiostation, pedal position, vehicle temperature, steering wheel andsteering column position, etc.

One advantage of using only the height and weight is that it avoids thenecessity of the seat manufacturer from having to interact with theheadliner manufacturer, or other component suppliers, since all of themeasuring transducers are in the seat. This two characteristic system isgenerally sufficient to distinguish drivers that normally drive aparticular vehicle. This system costs little more than the memorysystems now in use and is passive, i.e., it does not require action onthe part of the occupant after his initial adjustment has been made.

Instead of measuring the height and weight of the occupant, it is alsopossible to measure a combination of any two morphologicalcharacteristics and during a training phase, derive a relationshipbetween the occupancy of the seat, e.g., adult occupant, child occupant,etc., and the data of the two morphological characteristic. Thisrelationship may be embodied within a neural network so that during use,by measuring the two morphological characteristics, the occupancy of theseat can be determined.

Naturally, there are other methods of measuring the height of the driversuch as placing the transducers at other locations in the vehicle. Somealternatives are shown in other figures herein and include partial sideimages of the occupant and ultrasonic transducers positioned on or nearthe vehicle headliner. These transducers may already be present becauseof other implementations of the vehicle interior identification andmonitoring system described in the above referenced patent applications.The use of several transducers provides a more accurate determination oflocation of the head of the driver. When using a headliner mountedsensor alone, the exact position of the head is ambiguous since thetransducer measures the distance to the head regardless of whatdirection the head is. By knowing the distance from the head to anotherheadliner mounted transducer the ambiguity is substantially reduced.This argument is of course dependent on the use of ultrasonictransducers. Optical transducers using CCD, CMOS or equivalent arraysare now becoming price competitive and, as pointed out in the abovereferenced patent applications, will be the technology of choice forinterior vehicle monitoring. A single CMOS array of 160 by 160 pixels,for example, coupled with the appropriate pattern recognition software,can be used to form an image of the head of an occupant and accuratelylocate the head for the purposes of at least one of the inventionsdisclosed herein. It can also be used with a face recognition algorithmto positively identify the occupant.

FIG. 31 also illustrates a system where the seatbelt 27 has anadjustable upper anchorage point 390 which is automatically adjusted bya motor 391 to a location optimized based on the height of the occupant.In this system, infrared transmitter and CCD array receivers 6 and 9 arepositioned in a convenient location proximate the occupant's shoulder,such as in connection with the headliner, above and usually to theoutside of the occupant's shoulder. An appropriate pattern recognitionsystem, as may be resident in control circuitry 20 to which thereceivers 6 and 9 are coupled, as described above is then used todetermine the location and position of the shoulder. This information isprovided by control circuitry 20 to the seatbelt anchorage heightadjustment system 391 (through a conventional coupling arrangement),shown schematically, which moves the attachment point 390 of theseatbelt 27 to the optimum vertical location for the proper placement ofthe seatbelt 27.

The calculations for this feature and the appropriate control circuitrycan also be located in control module 20 or elsewhere if appropriate.Seatbelts are most effective when the upper attachment point to thevehicle is positioned vertically close to the shoulder of the occupantbeing restrained. If the attachment point is too low, the occupantexperiences discomfort from the rubbing of the belt on his or hershoulder. If it is too high, the occupant may experience discomfort dueto the rubbing of the belt against his or her neck and the occupant willmove forward by a greater amount during a crash which may result in hisor her head striking the steering wheel. For these reasons, it isdesirable to have the upper seatbelt attachment point located slightlyabove the occupant's shoulder. To accomplish this for various sizedoccupants, the location of the occupant's shoulder should be known,which can be accomplished by the vehicle interior monitoring systemdescribed herein.

Many luxury automobiles today have the ability to control the angle ofthe seat back as well as a lumbar support. These additional motions ofthe seat can also be controlled by the seat adjustment system inaccordance with the invention. FIG. 32 is a view of the seat of FIG. 24showing motors 392 and 393 for changing the tilt of the seat back andthe lumbar support. Three motors 393 are used to adjust the lumbarsupport in this implementation. The same procedure is used for theseadditional motions as described for FIG. 24 above.

An initial table is provided based on the optimum positions for varioussegments of the population. For example, for some applications the tablemay contain a setting value for each five percentile of the populationfor each of the 6 possible seat motions, fore and aft, up and down,total seat tilt, seat back angle, lumbar position, and headrest positionfor a total of 120 table entries. The second table similarly wouldcontain the personal preference modified values of the 6 positionsdesired by a particular driver.

The angular resolution of a transducer is proportional to the ratio ofthe wavelength to the diameter of the transmitter. Once threetransmitters and receivers are used, the approximate equivalent singletransmitter and receiver is one which has a diameter approximately equalto the shortest distance between any pair of transducers. In this case,the equivalent diameter is equal to the distance between transmitter 354or 355 and 353. This provides far greater resolution and, by controllingthe phase between signals sent by the transmitters, the direction of theequivalent ultrasonic beam can be controlled. Thus, the head of thedriver can be scanned with great accuracy and a map made of theoccupant's head. Using this technology plus an appropriate patternrecognition algorithm, such as a neural network, an accurate location ofthe driver's head can be found even when the driver's head is partiallyobscured by a hat, coat, or hairdo. This also provides at least oneother identification morphological characteristic which can be used tofurther identify the occupant, namely the diameter of the driver's head.

In an automobile, there is an approximately fixed vertical distancebetween the optimum location of the occupant's eyes and the location ofthe pedals. The distant from a driver's eyes to his or her feet, on theother hand, is not the same for all people. An individual driver nowcompensates for this discrepancy by moving the seat and by changing theangle between his or hers legs and body. For both small and largedrivers, this discrepancy cannot be fully compensated for and as aresult, their eyes are not appropriately placed. A similar problemexists with the steering wheel. To help correct these problems, thepedals and steering column should be movable as illustrated in FIG. 33which is a plan view similar to that of FIG. 31 showing a driver anddriver seat with an automatically adjustable steering column and pedalsystem which is adjusted based on the morphology of the driver.

In FIG. 33, a motor 394 is connected to and controls the position of thesteering column and another motor 395 is connected to and controls theposition of the pedals. Both motors 394 and 395 are coupled to andcontrolled by control circuit 254 wherein now the basic table ofsettings includes values for both the pedals and steering columnlocations.

The settings may be determined through experimentation or empirically bydetermining an optimum position of the pedals and steering wheel fordrivers having different morphologies, i.e., different heights,different leg lengths, etc.

More specifically, as shown in FIG. 33A, the morphology determinationsystem 430 determines one or more physical properties or characteristicsof the driver 30 which would affect the position of the steering column,e.g., leg length, height, and arm length. The determination of theseproperties may be obtained in any of the manners disclosed herein. Forexample, height may be determined using the system shown in FIG. 24. Leglength and arm length may be determined by measuring the weight, height,etc of the driver and then using a table to obtain an estimated oraverage leg length or arm length based on the measured properties. Inthe latter case, the control circuit 431 could obtain the measurementsand include data for the leg length and arm length, or would includedata on the position of the steering wheel for the measured driver,i.e., the table of settings.

In either case, the control system 431 is provided with the setting forthe steering wheel and if necessary, directs the motor 394 to move thesteering wheel to the desired position. Movement of the steering wheelis thus provided in a totally automatic manner without manualintervention by the driver, either, by adjusting a knob on the steeringwheel or by depressing a button.

Although movement of the steering wheel is shown here as beingcontrolled by a motor 394 that moves the steering column fore and aft,other methods are sometimes used in various vehicles such as changingthe tilt angle of the steering column or the tilt angle of the steeringwheel. Naturally, motors can be provided that cause these other motionsand are contemplated by at least one of the inventions disclosed hereinas is any other method that controls the position of the steering wheel.For example, FIG. 33B shows a schematic of a motor 429 which may be usedto control the tilt angle of the steering wheel relative to the steeringcolumn.

Regardless of which motor or motors are used, the invention contemplatesthe adjustment or movement of the steering wheel relative to the frontconsole of the vehicle and thus relative to the driver of the vehicle.This movement may be directly effective on the steering wheel (via motor429) or effective on the steering column and thus indirectly effectiveon the steering wheel since movement of the steering column will causemovement of the steering wheel. Additionally when the ignition is turnedoff the steering wheel and column and any other adjustable device orcomponent can be automatically moved to a more out of the way positionto permit easier ingress and egress from the vehicle, for example.

The steering wheel adjustment feature may be designed to be activatedupon detection of the presence of an object on the driver's seat. Thus,when a driver's first sits on the seat, the sensors could be designed toinitiate measurement of the driver's morphology and then control themotor or motors to adjust the steering wheel, if such adjustment isdeemed necessary. This is because an adjustment in the position of thesteering wheel is usually not required during the course of driving butis generally only required when a driver first sits in the seat. Thedetection of the presence of the driver may be achieved using the weightsensors and/or other presence detection means, such as using thewave-based sensors, capacitance sensors, electric field sensors, etc.

The eye ellipse discussed above is illustrated at 360 in FIG. 34, whichis a view showing the occupant's eyes and the seat adjusted to place theeyes at a particular vertical position for proper viewing through thewindshield and rear view mirror. Many systems are now under developmentto improve vehicle safety and driving ease. For example, night visionsystems are being sold which project an enhanced image of the road aheadof the vehicle onto the windshield in a “heads-up display”. The mainproblem with the systems now being sold is that the projected image doesnot precisely overlap the image as seen through the windshield. Thisparallax causes confusion in the driver and can only be corrected if thelocation of the driver's eyes is accurately known. One method of solvingthis problem is to use the passive seat adjustment system describedherein to place the occupant's eyes at the optimum location as describedabove. Once this has been accomplished, in addition to solving theparallax problem, the eyes are properly located with respect to the rearview mirror 55 and little if any adjustment is required in order for thedriver to have the proper view of what is behind the vehicle. Currentlythe problem is solved by projecting the heads-up display onto adifferent portion of the windshield, the bottom.

Although it has been described herein that the seat can be automaticallyadjusted to place the driver's eyes in the “eye-ellipse”, there are manymanual methods that can be implemented with feedback to the drivertelling him or her when his or her eyes are properly position. At leastone of the inventions disclosed herein is not limited by the use ofautomatic methods.

Once the morphology of the driver and the seat position is known, manyother objects in the vehicle can be automatically adjusted to conform tothe occupant. An automatically adjustable seat armrest, a cup holder,the cellular phone, or any other objects with which the driver interactscan be now moved to accommodate the driver. This is in addition to thepersonal preference items such as the radio station, temperature, etc.discussed above.

Once the system of at least one of the inventions disclosed herein isimplemented, additional features become possible such as a seat whichautomatically makes slight adjustments to help alleviate fatigue or toaccount for a change of position of the driver in the seat, or a seatwhich automatically changes position slightly based on the time of day.Many people prefer to sit more upright when driving at night, forexample. Other similar improvements based on knowledge of the occupantmorphology will now become obvious to those skilled in the art.

FIG. 30 shows a flow chart of one manner in the arrangement and methodfor controlling a vehicle component in accordance with the inventionfunctions. A measurement of the morphology of the occupant 30 isperformed at 396, i.e., one or more morphological characteristics aremeasured in any of the ways described above. The position of the seatportion 4 is obtained at 397 and both the measured morphologicalcharacteristic of the occupant 30 and the position of the seat portion 4are forwarded to the control system 400. The control system considersthese parameters and determines the manner in which the component 401should be controlled or adjusted, and even whether any adjustment isnecessary.

Preferably, seat adjustment means 398 are provided to enable automaticadjustment of the seat portion 4. If so, the current position of theseat portion 4 is stored in memory means 399 (which may be a previouslyadjusted position) and additional seat adjustment, if any, is determinedby the control system 400 to direct the seat adjustment means 398 tomove the seat. The seat portion 4 may be moved alone, i.e., consideredas the component, or adjusted together with another component, i.e.,considered separate from the component (represented by way of the dottedline in FIG. 30).

Although several preferred embodiments are illustrated and describedabove, there are other possible combinations using different sensorswhich measure either the same or different morphologicalcharacteristics, such as knee position, of an occupant to accomplish thesame or similar goals as those described herein.

It should be mentioned that the adjustment system may be used inconjunction with each vehicle seat. In this case, if a seat isdetermined to be unoccupied, then the processor means may be designed toadjust the seat for the benefit of other occupants, i.e., if a frontpassenger side seat is unoccupied but the rear passenger side seat isoccupied, then adjustment system could adjust the front seat for thebenefit of the rear-seated passenger, e.g., move the seat base forward.

In additional embodiments, the present invention involves themeasurement of one or more morphological characteristics of a vehicleoccupant and the use of these measurements to classify the occupant asto size and weight, and then to use this classification to position avehicle component, such as the seat, to a near optimum position for thatclass of occupant. Additional information concerning occupantpreferences can also be associated with the occupant class so that whena person belonging to that particular class occupies the vehicle, thepreferences associated with that class are implemented. Thesepreferences and associated component adjustments include the seatlocation after it has been manually adjusted away from the positionchosen initially by the system, the mirror location, temperature, radiostation, steering wheel and steering column positions, pedal positionsetc. The preferred morphological characteristics used are the occupantheight from the vehicle seat, weight of the occupant and facialfeatures. The height is determined by sensors, usually ultrasonic orelectromagnetic, located in the headrest, headliner or anotherconvenient location. The weight is determined by one of a variety oftechnologies that measure either pressure on or displacement of thevehicle seat or the force in the seat supporting structure. The facialfeatures are determined by image analysis comprising an imager such as aCCD or CMOS camera plus additional hardware and software.

The eye tracker systems discussed above are facilitated by at least oneof the inventions disclosed herein since one of the main purposes ofdetermining the location of the driver's eyes either by directlylocating them with trained pattern recognition technology or byinferring their location from the location of the driver's head, is sothat the seat can be automatically positioned to place the driver's eyesinto the “eye-ellipse”. The eye-ellipse is the proper location for thedriver's eyes to permit optimal operation of the vehicle and for thelocation of the mirrors etc. Thus, if the location of the driver's eyesare known, then the driver can be positioned so that his or her eyes areprecisely situated in the eye ellipse and the reflection off of the eyecan be monitored with a small eye tracker system. Also, by ascertainingthe location of the driver's eyes, a rear view mirror positioning devicecan be controlled to adjust the mirror 55 to an optimal position. Seesection 6.5 of the parent '881 application.

7.3 Rear Impacts

Rear impact protection is also discussed elsewhere herein. Arear-of-head detector is illustrated in FIG. 24. This detector, whichcan be one of the types described above, is used to determine thedistance from the headrest to the rearmost position of the occupant'shead and to therefore control the position of the headrest so that it isproperly positioned behind the occupant's head to offer optimum supportduring a rear impact. Although the headrest of most vehicles isadjustable, it is rare for an occupant to position it properly if atall. Each year there are in excess of 400,000 whiplash injuries invehicle impacts approximately 90,000 of which are from rear impacts(source: National Highway Traffic Safety Admin.). A properly positionedheadrest could substantially reduce the frequency of such injuries,which can be accomplished by the head detector of at least one of theinventions disclosed herein. The head detector is connected to theheadrest control mechanism and circuitry. This mechanism is capable ofmoving the headrest up and down and, in some cases, rotating it fore andaft.

7.4 Monitoring of other Vehicles such as Cargo Containers, TruckTrailers and Railroad Cars

Monitoring other vehicles and assets using the inventions disclosedabove, alone or in conjunction with inventions disclosed in the '979application, is discussed in section 7.4 of the '979 application.

Although several preferred embodiments are illustrated and describedabove, there are possible combinations using other signals and sensorsfor the components and different forms of the neural networkimplementation or different pattern recognition technologies thatperform the same functions which can be utilized in accordance with theinvention. Also, although the neural network and modular neural networkshave been described as an example of one means of pattern recognition,other pattern recognition means exist and still others are beingdeveloped which can be used to identify potential component failures bycomparing the operation of a component over time with patternscharacteristic of normal and abnormal component operation. In addition,with the pattern recognition system described above, the input data tothe system may be data which has been pre-processed rather than the rawsignal data either through a process called “feature extraction” or byvarious mathematical transformations. Also, any of the apparatus andmethods disclosed herein may be used for diagnosing the state ofoperation or a plurality of discrete components.

Although several preferred embodiments are illustrated and describedabove, there are possible combinations using other geometries, sensors,materials and different dimensions for the components that perform thesame functions. At least one of the inventions disclosed herein is notlimited to the above embodiments and should be determined by thefollowing claims. There are also numerous additional applications inaddition to those described above. Many changes, modifications,variations and other uses and applications of the subject inventionwill, however, become apparent to those skilled in the art afterconsidering this specification and the accompanying drawings whichdisclose the preferred embodiments thereof. All such changes,modifications, variations and other uses and applications which do notdepart from the spirit and scope of the invention are deemed to becovered by the invention which is limited only by the following claims.

1. A method for controlling outflow of fluid from a vehicular airbag,comprising: deploying the airbag toward an occupant prior to or duringan accident involving the vehicle; detecting contact between the airbagand the occupant by means of a sensor; and controlling outflow of fluidfrom the airbag based on the detected contact by the sensor.
 2. Themethod of claim 1, wherein the outflow of fluid is controlled tomaintain acceleration of the occupant's chest below a predeterminedmaximum value.
 3. The method of claim 1, further comprising: forecastingseverity of the accident for which the airbag is deploying; and settingthe predetermined maximum value based on the forecast severity of theaccident.
 4. The method of claim 1, further comprising arranging a ventin the airbag, outflow of fluid from the airbag being controlled byadjusting the vent size.
 5. The method of claim 1, further comprising:forecasting severity of the accident for which the airbag is deploying;determining an average chest acceleration to cause the occupant to havethe same acceleration as a passenger compartment of the vehicle in whichthe occupant is situated; and initially controlling outflow of fluidfrom the airbag to provide the average chest acceleration, the outflowof fluid from the airbag being controlled to provide for an adjustmentof the initial control based on the actual chest acceleration.
 6. Themethod of claim 1, further comprising: determining whether the occupantis wearing a seatbelt; and adjusting the outflow of fluid from theairbag based on whether the occupant is wearing the seatbelt.
 7. Themethod of claim 1, wherein contact between the airbag and the occupantis detected by analyzing deceleration of the airbag.
 8. The method ofclaim 7, wherein the sensor is an accelerometer arranged on a surface ofthe airbag to sense deceleration of the airbag.
 9. The method of claim7, wherein the sensor is a pressure sensor arranged to sense thepressure in the airbag which is correlatable to the deceleration of theairbag.
 10. The method of claim 1, wherein the sensor is arranged inconnection with the airbag to sense a property of the airbag or a partthereof.
 11. The method of claim 10, wherein the airbag includes atleast one tether between opposed inner surfaces, the sensor beingarranged to measure tension in the at least one tether.
 12. A system forcontrolling outflow of fluid from a vehicular airbag, comprising: anairbag arranged to deploy toward an occupant prior to or during anaccident involving the vehicle; a sensor system for detecting contactbetween said airbag and the occupant; and a fluid outflow control systemfor controlling outflow of fluid from said airbag based on the contactbetween said airbag and the occupant as detected by said sensor system.13. The system of claim 12, wherein said control system comprises anexit control valve or vent arranged in said airbag.
 14. The system ofclaim 12, wherein said sensor system is arranged to sense decelerationof said airbag whereby analysis of the sensed deceleration provides anindication of contact between said airbag and the occupant.
 15. Thesystem of claim 14, wherein said sensor system includes an accelerometerarranged on a surface of said airbag facing the occupant and whichsenses deceleration of said airbag.
 16. The system of claim 12, whereinsaid sensor system is arranged to sense pressure in said airbag wherebyanalysis of the sensed pressure provides an indication of contactbetween said airbag and the occupant.
 17. The system of claim 12,wherein said airbag includes at least one tether between opposed innersurfaces, said sensor system comprising at least one sensor arranged tomeasure tension in said at least one tether from which contact betweensaid airbag and the occupant is detectable, said control systemincluding an exit control valve or vent arranged in connection with saidairbag to vent fluid from said airbag and a control module coupled tosaid at least one sensor to control said exit control valve or vent. 18.A method for controlling deployment of a vehicular airbag, comprising:detecting an accident involving the vehicle; deploying the airbag towardan occupant prior to or during the accident at initial deploymentconditions; detecting contact between the airbag and the occupant bymeans of a sensor; determining adjusted deployment conditions based onthe detected contact; and adjusting the deployment of the airbag toprovide the adjusted deployment conditions.
 19. The method of claim 18,further comprising: forecasting severity of the accident; anddetermining the initial deployment conditions based on the forecastseverity of the accident.
 20. The method of claim 18, further comprisingdetermining whether the occupant is wearing a seatbelt; and determiningthe adjusted deployment conditions based on whether the occupant iswearing the seatbelt.